The probe is hinged on the ring to get the perfect angle for you and making insertion slightly easier. It can be a useful aid in helping you adjust to urethral insertions for Electro Play, Catheterisation, CBT and other penis play scenarios. The glans ring sizes are 25mm, 28mm, 30mm and 32mm (sizes are internal diameter). The probe measures 7cm on all of the probes.Use caution when using any product of this type considering where it goes, pay attention to cleanliness and hygiene. We recommend sterilisation before every usage, either by putting it in a pressure cooker or hot oven.