After removing the opening seal sharp outlines of vagina and anus are retained. This leads to injury of the penis foreskin, because the holes are not circular but narrow sharp-edged ellipses. Possible that the doll was built for thin penises smaller diameter 35mm. Hard to use for adult men!
The durability was limited to 5x normal use, since the doll suddenly lost a lot of air. For men this doll is to use less well ?!