Far be it from me to disagree with Al on SF stuff /ubbthreads/images/graemlins/str.gif, but I bought 3 G2Z LOTC's for G2s, one for mine, and two for others' G2s (that were Xmas presents from me. One for my best friend and one for my dad). I just called SF direct and said "I want to order the tailcap from a G2Z." Not sure about part#. They work fine. The look is not as "clean" as the stock G2 cap (there's a bit more space between the cap and the body, like where a lanyard ring would go), but the lock-out adds to the utility of such a great light. Some combinations of individual G2 bodies and G2Z caps are a tad looser than I like, but that's easily fixed with an additional O-ring, a-la the millenium series. YMMV.