Abstract: A compression implant to resist the flow of urine through the urethra comprising a cap, an external planar pressure face on the cap, a base, an external bearing face on the base, and a peripheral wall continuously interconnecting the cap and the base. A peripheral fold in the peripheral wall enables the face to move toward and away from the base by changing the shape of the fold without elastic stretching of the material which forms the wall. The cap, base and peripheral wall together define an internal cavity which can be filled with an adjustably variable amount of fluid whereby to adjust the firmness of the capsule and thereby to adjust the force which it exerts against the urethra after implantation.