The one-inch Nub is very comfortable

When I wrote about chastity device fit several years ago, my advice was based on cages like the Jail Bird or Holy Trainer. They are simple containers for the penis. Over the years, I learned that the shorter the cage, the better the fit. Since we started writing about short cages, more have come on the market. Famously, Holy Trainer started selling their “Nub”. This device is only one inch long. I found it comfortable to wear. Other guys who generally wear longer, custom cages also like it. It’s so short, the urethra pokes out of the front like two little lips. I didn’t find that a problem.

The bottom line is that so long as the diameter of the cage is close to the measured diameter of the shaft, the length isn’t important. Cages like the Nub are very comfortable. I had my Jail Bird shortened to a one-inch cage and it fit like a glove. Bear in mind that a one-inch cage doesn’t mean there is only one inch of room for your penis. You have to add in the thickness of the base ring and the gap left for the scrotum. Depending on the cage, that can add another inch.

There is a new kind of chastity device. This type has a separate “chamber” for the glans (head). The way it works is that there is a ring or shelf inside the device that “catches” the glans where it gets wider than the shaft. There is a sort of groove under the head of the penis. These devices add a ring or shelf that fits into the groove. It prevents the head from slipping back. I am aware of two makers who build devices like this: the Cherry Keeper, and the Evotion Wearables line of devices. Both makers use 3D printing to produce their devices.

evotion orion ring to hold penis head in place

I love this feature. By “capturing” the head of the penis, it stays put pressing the end of the cage. The shaft can expand and contract without changing that. Great idea! Unfortunately, I didn’t fully understand the implications this design has on fit.

When I sized my Evotion Orion male chastity device, I assumed that the same sort of very short cage would work best for me. So, I specified a shaft length of 31mm (approx 1-1/4 in.). This is the distance from where my penis joins my abdomen (top side) to the bottom of the glans. This is roughly the same sort of fit as my very short Jail Bird.

The Orion goes on in three sections: the base ring, shaft tube, and head cover. The shaft tube has a ring at the front designed to capture the groove under the glans. (See image, above) Since I gave a very short measurement, I had to really pull from behind the base ring to get the shaft back so that just the head protruded. Doing this puts a lot of stress on delicate skin. Since the glans was held in place by the ring, there was no reason for this very short section.

This is the my Orion with the “short” shaft section, You can see that the head (glans) is captured by the shaft section so that it will remain in place if my penis shrinks further.

After hurting myself with the stretching exercise, it finally dawned on me that I didn’t need any shaft compression to keep the head in place. The device could be considerably longer without causing any problems. I remeasured my penis when flaccid, but not coming-out-of-cold-water shrunk.The abdomen-to-glans distance was 49mm (1.9 in). That is a big difference! I ordered a new, longer shaft section using this measurement. That would make the abdomen-to-tip about 3 inches.

Bear in mind that Evotion wants a measurement along the top of the penis. Mature Metal and other cage makers want the shaft measurement on the bottom side, measuring from the scrotum to the tip. The Cherry Keeper wants that bottom measurement from scrotum to base of the glans and then the glans length. That allows locating the “shelf” that captures the glans.

It turns out that we have two measurement strategies depending on the device design. If getting a “free cage” design where there is no retainer for the glans, I think shorter is better. I love my 1-inch Jail Bird and Holy Trainer Nub. They are comfortable and the head of my penis stays front-and-center where it belongs.

When it comes to devices that have a “head capture” feature, the strategy needs to be different. Shaft length can be longer. I made mine the same length as my penis is when at rest. It isn’t the shortest it gets and isn’t the longest. It’s an average from a week’s worth of measurements. The glans size stays fairly constant for a flaccid penis. The length measurement should be as accurate as possible. The same is true for the diameter. Glans diameter is measured at the widest part, just above the groove.

Measurements have always been important when fitting a male chastity device. Always make them when completely flaccid (soft). Don’t leave room for an erection. The devices are designed to prevent them. The better the fit, the more comfortable and effective the device. Take your time. Remember, you will be living in this cage 24/7.


  1. Good post on sizing for a cage! But I wanted to wish you a happy birthday!! So while I am behind in reading your posts, I read this one out of order so I could wish you a good birthday. May your day go very well with lots of attention from Mrs. Lion!

    1. Author

      Thank you for the good wishes! I may be healed enough to enjoy some attention from Mrs. Lion. Great timing!

  2. Been listening to your wonderful podcasts and found you here. I have been happily in Chastity since January of this year. I unfortunately haven’t been able to stop occasionally pleasuring myself even with my 2” Jailbird on. It seriously upsets me that I can do this. I have had sexual trauma in my youth and this is actually cheaper than counseling. So I was wondering if you had any suggestions on what I Cage could possibly help me out. I seen Evolution wearables has a LeSac and was hoping that or Orion would prevent this . Thanks again keep up the great work

    1. Author

      Thank you. Good luck!

  3. Reading this post, I understand that cage calibration is not a very easy task. Especially considering that different manufacturers offer different measurement methods.
    And I join in the congratulations on your birthday!

    1. Author

      Thanks for the good wishes!

  4. And yet, the penis in the chastity device looks somehow unhealthy.

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