Rimba Bondage Play - Ribbed Urethral Plug This urethral plug has stimulating ridges that the user will feel when inserting the plug, providing an intense orgasm. The plug is hollow allowing moisture to come out. The insertable length is 40 mm. The thickness varies between 8 mm and 12 mm. Note: Always sterilize and clean the plug before use. To ensure a smooth insertion, we recommend using lubricant.