Ohnut and depth-limiting rings: a tool for deep pain during sex

The Ohnut is a set of soft, stackable rings worn at the base of a penis or toy that limit how deep penetration can go. It belongs to a wider category of depth-limiting devices, sometimes called depth buffers, used to reduce deep pain during sex. They do not treat the cause of pain, but a small randomized trial suggests they can make sex more comfortable for people with deep pain, particularly from endometriosis.

The problem it addresses: deep pain

Pain during sex is often split into two kinds. Entry pain is felt at the vaginal opening. Deep pain, sometimes called collision dyspareunia, is felt inside the pelvis when penetration reaches a certain depth or hits a tender area, often the cervix, the area behind it, or the deep pelvic floor.

Common causes of deep pain include:

• Endometriosis, which affects around half of people with the condition during sex
• A tense or tender pelvic floor
• Pelvic inflammatory disease or other infections
• Ovarian cysts, fibroids or scar tissue after surgery
• Changes after a hysterectomy
• Simply a difference in partners' anatomy

For many people, shallower penetration is comfortable while deeper strokes hurt. A depth limiter targets exactly that gap.

What the Ohnut is

The Ohnut is a commercially available set of interlocking rings made from a soft, flexible, body-safe polymer. The rings are worn at the base of the penis, or of a toy, and they compress slightly on contact, acting as a cushioned buffer. Users can wear one ring for a small reduction in depth or link several together for a larger reduction.

The rings are designed to sit comfortably rather than constrict, which is the main difference from constriction rings designed to affect erections.

The general category: depth buffers

The Ohnut is the best known product in this category, but the idea itself is simple and older than any single brand. Depth-limiting approaches include:

• Soft wearable rings or bumpers that sit at the base of the penis or toy
• Positions that naturally limit depth, such as spooning or side-lying
• Using a hand around the base of the penis as a temporary stop
• Toys or harnesses chosen for a shorter insertable length

Devices have the advantage of freeing up positions and hands, and of making depth predictable, which can reduce anxiety in the person who expects pain.

What the research says

Evidence is limited but encouraging. A pilot randomized controlled trial published in Sexual Medicine in 2024, run by the BC Women's Centre for Pelvic Pain and Endometriosis in Vancouver, studied couples where one partner had surgically confirmed endometriosis and deep pain during sex.

Key findings:

• Couples using the Ohnut used it in about seven out of ten sexual encounters during the study period.
• Both patients and partners rated it as highly acceptable.
• After accounting for baseline pain, deep pain scores were significantly lower in the group using the Ohnut than in the waitlist group.

The trial was small, with 17 couples completing it, and had strict entry criteria. The researchers describe the results as preliminary evidence and plan a larger study. So the device is reasonably described as a promising self-management tool for deep pain, not a proven treatment for all causes of pain.

Who might consider a depth limiter

A depth limiter may be worth trying if:

• Pain only appears with deeper penetration, and shallow penetration is comfortable
• Certain positions are painful because they allow more depth
• You have a diagnosis such as endometriosis and are looking for practical ways to stay sexually active alongside medical care
• Fear of a sudden painful thrust is making it hard to relax

It is less likely to help with entry pain from vaginismus, vulvodynia or vaginal dryness.

Using one well

• Combine with lube. Friction is still a factor, so a good water-based lube helps.
• Start with more buffering, then reduce it if that feels comfortable.
• Talk about it beforehand. Partners usually adjust quickly, and in the research, partners rated the device as acceptable too. Our guide to talking about pain with a partner can help with the conversation.
• Clean according to the material, usually with warm water and mild soap.
• Remove it if it causes numbness, tightness or skin irritation for either partner.

Questions to ask a clinician

If you are considering a depth limiter, a short conversation with a gynecologist or pelvic floor physical therapist can help. Useful questions include whether your pain pattern fits deep dyspareunia, whether anything needs investigating first, and whether pelvic floor work could reduce pain alongside the device.

What the device does not do

A depth limiter changes only one thing: how far penetration goes. It does not add lubrication, relax the pelvic floor, treat endometriosis or reduce inflammation. It is also not designed for anal use or for contraception, and it offers no protection against sexually transmitted infections, so condoms are still needed where relevant. Its value is in making sex predictable and more comfortable while other causes are addressed.

Part of the picture, not the whole picture

Deep pain has causes, and some of them need medical treatment. A depth limiter can make sex more comfortable while those are investigated or managed, alongside pelvic floor therapy for muscle tension and medical care from a gynecologist. See a GP if deep pain is new, getting worse, comes with bleeding after sex, or occurs with painful periods or pelvic pain outside of sex. For an overview of causes, read our guide to dyspareunia.