Unlike long, non-stretchy and unyielding rubber penis sheath 1 this one is made out of soft and supple latex, so getting inside is easy. It is also short, not longer than 8-9cm, hence full erection is not achievable. From the self-bondage point of view, I take it as an additional bonus. But on the other hand, you need something to keep the sheath in place. For example, electrical tape, glue or pants with anal sheath and cock ring

Check eBay for penis sheaths.