How to measure your penis to select the right chastity cage



Which BON4 Steel Chastity Cage is for You?

Selecting and fitting a BON4 penis cage is an initial part of the fun in chastity. Your Keyholder can make your selection an arousing or humiliating game.
Basically there are 2 ways to select the right cage;

  1. You select one of the BON4M Series based on your, or your Keyholders findings, as explained on Sizing is easy.
  2. Measuring your penis.To begin, take the correct measurement of the penis to be confined. A penis can be measured in several dimensions and for different purposes. The most common measurement is of an erection, for various purposes from bragging to humiliation, but in fact, the erected size is of no importance at all when it concerns selecting the right cage.
Measuring for a chastity cage is a bit different and simple. All BON4 steel cages have two critical dimensions, the retainer ring diameter and the cage length.

  • Retainer ring: You need not clumsily wrap a dressmaker’s tape behind your scrotum before ordering your cage.
    We include a large selection of different diameter rings, all of which rotate a full 360°, to allow easy placement.
    Experiment to find the ring to give you the best combination of comfort and security. You and your Keyholder should expect a few trials to find the best ring for long-term wear.
    After that, keep the other rings separate, and you’ll never get pinched by a tight ring. Nor can you escape from a loose one!
  • Cage length: Fortunately, there is only one critical measurement to determine the correct BON4 cage to purchase.
    Measure a flaccid penis on the underside of your shaft. This is the part of your genitals that fits in the cage.
    Place a ruler against your scrotum and use it to lift your flaccid shaft.
    The length of your shaft can be read from above. It’s that simple.
    If the imminent loss of your freedom makes you too excited for proper measurement, your Keyholder may know some moves to make you shrivel up.
    If not, or if you enjoy that type of play, wrap that proud boy in an ice pack, then measure.
Choosing the right cage(s)

Now that you know your shaft length, select the correct cage, remembering your Keyholder has the final say.
The BON4M will contain most men. However, your Keyholder may have other ideas. Perhaps you will be stuffed into the BON4Micro or allowed some frustrating partial growth in the BON4ML.
For the really big boys there’s the BON4MXL, an extra large stainless steel cock cage. We also offer complete BON4Mplus male chastity packages which contain 2 different cock cages. These plus packages offer extra fun & options for you and particularly your Keyholder.
Here is a table of recommended size ranges for comfortable fit, neither for punishment or humiliation nor to allow partial erections.

Flaccid dick length in inches 1.4″ – 2.6″ 2.6″ – 4.0″ 4.0″ – 5.2″ 5.2″ – 6.6″
Flaccid dick length in mm 35 – 66 mm 66 – 102 mm 102 – 132 mm 132 – 168 mm
Flaccid dick length in inches Flaccid dick length in mm
BON4Micro 1.4″–2.6″ 35–66
BON4M 2.6″–4.0″ 66–102
BON4ML 4.0″–5.2″ 102–132
BON4MXL 5.2″–6.6″ 132–168


Now, select and order the chastity cage or cages you need to be submissive as your Keyholder expects.

Selecting pins and spacers

Each BON4M cage comes with different sizes of pins to hold the ring to the cage. Each pin has a hole in the end for the lock. A spacer fits each ring, determining the distance between the ring and the cage. You and your Keyholder must experiment to discover which length works best for you.

Tiny, cylindrical spacers can roll away if unsecured. To secure unused spacers, place them on the corresponding pin and pass a paper clip or other retainer through the lock hole.
Rejoice in Your Submission.

View our hinged BON4M Series instruction movie

Once caged, your submissive nature will be reinforced. You and your Keyholder will have a special bond others can’t share.

Care and Hygiene of Your BON4M Series Male Chastity Cage