To set the record straight, anal sex is not supposed to be painful (no, not even the first time). Anal sex is a sex act designed to pleasurably stimulate the nerve-rich anal rim and canal, as well as create a pleasurable sensation of fullness—emphasis on the pleasure intended. However, having satisfying anal sex—in particular, with penetration—can require a little forethought. And no, we’re not just talking about buying a good lube (though, let this serve as a reminder that lube is a must for all things butt play).

“Many people have to train the anal sphincter muscles at the entrance of the anal canal to relax enough to accept a toy or body part,” says anal surgeon Evan Goldstein, DO, founder of proctological and anal plastic surgery practice Bespoke Surgical and pleasure tool company Future Method. Failure to train these muscles ahead of anal penetration can make the whole shebang feel like trying to put a square peg into a tight, round hole (no matter the shape of the actual “peg,” per se). Luckily, for that, there are anal dilators, which are smooth, tubular medical devices placed inside the anus to gently stretch the surrounding muscles.

“Many people have to train the anal sphincter muscles at the entrance of the anal canal to relax enough to accept a toy or body part.” —Evan Goldstein, DO, anal surgeon

Below, learn exactly what anal dilators are, how they work, and how to use an anal dilator set to prime your butt for frictionless butt play of all sorts.

What are anal dilators, and what are they typically used for?

Anal dilators, sometimes known as rectal dilators, are dildo-shaped medical devices that are inserted into the anus to support the health, shape, and function of the anal canal, says Dr. Goldstein. In some cases, they are prescribed to help relieve elevated pressure in the anal canal, which can cause recurring hemorrhoids (enlarged or swollen veins in the lower rectum) or anal fissures (tiny tears in the lining of the anus), says Steven Lavender, a pelvic floor therapist with Bespoke Surgical. Using anal dilators can therefore help relieve these ailments, he says.

In other instances, anal dilators, like vaginal dilators (similar tools inserted into the vagina), are used in conjunction with pelvic floor physical therapy to alleviate pelvic floor dysfunction. “Pelvic floor issues like chronic prostatitis, endometriosis, and proctalgia fugax (severe, intermittent episodes of rectal cramps that can be triggered by menstruation) can create pain that can be quite debilitating,” says Lavender. And anal dilators, in addition to relaxing anal muscles, can soften tight pelvic floor muscles, which may help relieve some of the pain associated with the above conditions.

How can anal dilators be used to improve anal play and sex?

For anal play and penetration to feel good, the anal sphincter muscles—which consist of three ring-shaped muscles along the anal canal—have to relax, creating open space in the canal, says Dr. Goldstein. In fact, trying to penetrate an anal canal that is locked shut can injure the anal sphincter muscles by pushing them past their capacity. (It’s like a hamstring strain, but in your hiney.)

Like any other muscle, these sphincter muscles are capable of either contracting or relaxing at any point—but the tricky part is, for many people, anal sphincter proprioception can be challenging, says Lavender. Meaning, you might not be able to easily tell when you’re clenching or relaxing those butt muscles in the way that you’d certainly know if you were tensing or relaxing, say, your bicep.

To complicate things further, the sphincter muscles are also “innately geared toward staying shut (or being clenched) so that we don’t crap our pants,” says Dr. Goldstein. Plus, these muscles can get locked in a contracted position during day-to-day activities like sitting at a desk or squatting at the gym, he adds. “Together, these things can create considerable muscle tone in the anal sphincter region.” And as a result, it can be a struggle to relax those muscles enough to make anal sex actually possible and pleasurable.

“[Using anal dilators] will help you regulate between relaxing to the capacity that’s needed for anal sex and [closing the muscles] when needed for the rest of daily life.” —Dr. Goldstein

That’s where anal dilators come into play. Their function is to train those often-clenching anal sphincter muscles to relax, says Dr. Goldstein. They do this by giving you something physical to clench against, which provides clear feedback for those muscles, says Lavender, helping alert you to the fact that they’re indeed clenched. Over time, this can teach you to differentiate between the feeling of contracting versus relaxing your bum, “so that you can regulate between relaxing to the capacity that’s needed for anal sex and [closing the muscles] when needed for the rest of daily life,” says Dr. Goldstein.

An added bonus? “Anal dilators also help gently stretch the skin and tissues surrounding the anal muscles,” says Dr. Goldstein. And a certain degree of skin elasticity is required for pleasurable anal penetration, he says. (But, before you ask…no, anal dilators will not permanently stretch out your butthole.)

How is an anal dilator different from an anal sex toy?

Anal dilators aren’t sex toys; they’re medical tools. So, while they can certainly be used to prep the butt for smoother, easier anal penetration, as noted above, they aren’t meant to be used as part of sex acts or for in-the-moment pleasure, like an anal-safe dildo or butt plug.

Instead, anal dilators are designed to give you access to future pleasure, says Dr. Goldstein. They typically come as a set of three or more dilators in incrementally larger sizes. “Anal dilators offer a stepwise progression so you can gradually strengthen, stretch, and train the anal skin and underlying muscles,” he explains. You want each dilator in a set to be just a smidge larger than the one before it, so that you don’t injure yourself when you graduate to the next size (more on how to use them below).

By contrast, butt plugs and dildos can be used as part of anal play—but are not designed to train the anal sphincter muscles to loosen up. “There is a common misconception that butt plugs and dildos can and should be left inside the anus for an extended period of time [right before or during sex],” says Dr. Goldstein. “But that only provides you with a sense of fullness; it doesn’t actually teach your anal sphincter muscles how to relax,” he says. (Plus, this can irritate the delicate anal lining, he says, making you more susceptible to infections and micro-tears of the anus.)

While dildos are also typically phallic in shape and butt plugs are often short, wide, or rounded, anal dilators are long, tapered, and smooth—designed to gently apply pressure to all three sets of anal sphincters. Like their sex-toy counterparts, they come in a variety of body-safe materials, but Dr. Goldstein recommends buying glass ones. Earlier this year, he launched the Future Method Glass Anal Dilator Set ($60) to offer a glass option for his patients, specifically because of the anus-loving benefits of going with glass.

Future Method Glass Anal Dilator Set — $60.00

“The friction that glass creates against the skin of the anal canal is more controlled and minimal compared to the friction created by other materials like silicone,” says Dr. Goldstein. And contrary to popular belief, you do not need to worry about a glass dilator (or glass sex toy, for that matter) breaking inside you, as they’re made of durable, body-safe borosilicate glass. “The extra weight of the glass [over other materials] also provides additional pressure against the skin and anal muscles,” adds Dr. Goldstein, which helps the dilators work more efficiently.

Glass is also compatible with all lubes, including silicone-based lube (which can’t be used with silicone dilators or toys). And that’s a big deal: Silicone lube is the option that sexperts recommend for anal sex since it’s typically thicker, more cushion-y, and longer-lasting than water- and oil-based lubricants.

How to use an anal dilator set to prepare your butt for more pleasurable anal sex

1. Take steps to relax your body

Start by lying down on your back and getting comfortable. Just as your traps, jaw, and shoulders can tense up when you’re stressed out, so can your bum-hole, says Dr. Goldstein. And that’s the last thing you want when you’re about to insert something into it.

You might even try masturbating first, he says. “Some people treat anal dilator use as ‘homework’ and don’t include self-pleasure, but if you want to get off before using a dilator (or after), go ahead.” Doing so may actually help relieve some of the pre-existing tension in your anal muscles, and therefore make dilation easier.

2. Load up on lube, then slide in the smallest dilator in the set

Dr. Goldstein’s advice for how to actually use an anal dilator starts with lathering a ton of silicone lube on both the dilator and your anus. Then, position the dilator at the entrance of your anal canal and rock it back and forth along the entrance to prime the first ring of sphincter muscles. Next, gently push the dilator inside until you feel pressure from the muscles in your butt. If (and when) you start to feel resistance from your body, try to consciously relax with a deep breath in order to accommodate more length. Finally, at the point of resistance, slowly remove the dilator in one continuous motion.

“Re-lubricate, and insert again with a similar technique of slowly moving in, meeting resistance, and then slowly pulling out,” says Dr. Goldstein, adding that most people will need to repeat this exercise four to six times before achieving full insertion. Keep it going for 12 to 15 repetitions, in total, for a complete session—or until it becomes uncomfortable or irritating, whichever comes first.

3. Keep on using the dilator set, going up in size

For optimal results, Dr. Goldstein recommends using the smallest dilator in your set two to three times per week for two weeks. Then, use a combination of both the small and medium dilators for the following two weeks.

Assuming you don’t experience any discomfort using the medium one, you can graduate to the larger dilator after that point. “All in all, it usually takes about four to six weeks of regular anal dilator use for a person to create the needed relaxation effect for pleasurable anal sex,” says Dr. Goldstein.

Even once you’ve mastered dilation, though, it’s a good idea to keep using dilators if anal play makes a regular (or regular-ish) appearance in your sex life, Dr. Goldstein adds. Otherwise, the muscles and skin will eventually revert to their natural tone from before you started…in which case, he says, you’ll need to start the process over again.