HolyTrainer Nub V2
The HolyTrainer Nub V2 earns a LockedCage Score of 8.0/10 with a perfect 10/10 discretion rating — the highest of any cage we tested. At 26mm (1.02 in), it is 9mm shorter than the Nano and 34% smaller than the Cobra Micro, making it the smallest production chastity cage available. Best for experienced users who have already sized down through the Nano and prioritize total invisibility under clothing over urination convenience.
Check Price on HolyTrainerHolyTrainer Nub V2 Review: The Invisible Cage
At just 26mm (1 inch) long, the Nub challenges everything you think you know about chastity sizing. It shouldn't work, but it does — and users report it's surprisingly comfortable. Here's the data on extreme micro-sizing.
Reviewed by LockedCage Team · Feb 13, 2026 · 8 min read · Based on 623 user reports
LockedCage Score
8.0 / 10
Literally invisible under clothes
Surprisingly good for the right fit
Tight fit reduces pullout risk
Small opening needs careful cleaning
Must sit to urinate
Verdict: Maximum Discretion
For experienced users who prioritize invisibility over convenience.
Is the Nub Right For You?
The Nub is not a beginner cage. It's for users who have tried smaller cages like the HolyTrainer Nano and want to push further into micro-sizing. If you're comparing flat-profile options, see also the Cobra Micro Flat. The psychological effect of extreme compression is the main appeal — this cage makes your penis effectively disappear.
Why Users Choose the Nub
- True invisibility: Zero visible bulge under any clothing
- Psychological intensity: Extreme compression creates unique mental state
- Less pressure: Flat profile reduces forward push compared to longer cages
- Sleep comfort: Many report better sleep than with larger devices
- Security through compression: Tight fit makes pullout genuinely difficult
The Trade-offs
- Urination challenges: You will need to sit; standing is nearly impossible
- Cleaning difficulty: Tight interior requires more attention to hygiene
- Not for beginners: Work up to this size; don't start here
- Specific anatomy required: Needs small flaccid size and low grower tendency
- Social adjustments: Public restrooms require planning and confidence
Nub Specifications
| Specification | HolyTrainer Nub |
|---|---|
| Cage Length (internal) | 26mm (1.02") |
| Internal Diameter | 33mm (1.3") |
| Material | Bio-resin (biosourced) |
| Lock Type | Integrated brass cylinder |
| Ring Options | 36, 40, 45, 50, 55mm |
| Weight | ~70g (varies by ring) |
| Recommended Flaccid Length | Under 1.5" (38mm) |
| Experience Level | Intermediate to Advanced |
User Experiences
“I was skeptical about going this small. After two weeks in the Nub, I can't imagine going back to a standard cage. The invisibility is addicting.”
“Urinating is a mess. I carry wet wipes everywhere now. But for the discretion? Worth it.”
“Started with the Standard, went to Small, then Nano, now Nub. Each step felt more right. The Nub just... fits.”
Common Questions
The Nub has an internal cage length of just 26mm (1.02 inches) and a diameter of 33mm (1.3 inches). It's designed for extreme micro-sizing — essentially compressing the penis into the smallest possible profile.
Surprisingly, yes — for the right anatomy. Users report that the Nub's flat profile creates less forward pressure than longer cages. However, urination is challenging (you'll need to sit) and cleaning requires more attention due to the tight fit.
Nub (26mm): For experienced users with small flaccid anatomy (under 1.5") seeking maximum discretion. Nano (35mm): Better for beginners to micro-sizing or those with 1.5-2.0" flaccid length.
Most users cannot. The 26mm length positions the urethral opening inside or at the very edge of the cage, making aiming difficult. Plan to sit for urination.
The extreme tight fit actually makes pullout more difficult than longer cages — there's simply less room to maneuver. However, no ball-trap device is truly inescapable without a piercing.
References
- [1]ISO 10993-5:2009 establishes in-vitro cytotoxicity testing requirements for medical devices with prolonged skin contact. Bio-resin materials that pass this standard demonstrate no cytotoxic effects during extended wear. — ISO 10993-5:2009 — Biological Evaluation of Medical Devices
- [2]FDA 21 CFR Part 177 defines acceptable polymers for repeated human contact. Biosourced resins meeting these thresholds are classified as body-safe for prolonged dermal exposure. — FDA 21 CFR 177 — Indirect Food Additives: Polymers
- [3]The ECHA Candidate List of Substances of Very High Concern (SVHC) identifies chemicals restricted in consumer products under EU REACH. Bio-resin formulations that avoid listed phthalates and BPA meet current EU safety thresholds. — European Chemicals Agency — SVHC Candidate List
- [4]HolyTrainer bio-resin is biosourced and hypoallergenic, designed for extended skin contact without irritation or allergic reaction. — HolyTrainer Official
See Also
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Ready to disappear?
The HolyTrainer Nub is for those who want maximum discretion and aren't afraid of extreme sizing.