How much of it do I actually fill?
Roughly the bottom half; the cavity runs to about midway and the rest is solid. That means the added length is real rather than depending on how far in you reach, and it also means the fit matters more than your own length does.
How is this different from a trimmable sleeve?
Different approach entirely. The Xtend It Kit is soft ULTRASKYN you cut to fit and adds one to three inches. This is firm PVC in one fixed size, built for maximum length rather than a tailored fit.
Will it stay on?
The seal does the work, which is why Doc Johnson recommends putting it on erect or semi-erect. There is no ball strap, so a loose fit will slip; if you want something anchored, look for an extender with a strap.
Does the wearer feel much?
Not much, and that is part of the point. With everything covered, sensation drops considerably, which is why this doubles as a stamina sleeve for people who finish sooner than they would like.
How do I clean it?
Wash it inside and out with warm water and mild soap after use, then dry it fully before storing it flat. PVC is porous, so it should not be shared between partners without a barrier.
