What I (also) like about IWC is the spare parts avaliablility, even if your watch is long discontinued. Had the strap already, however one of the connecting shoulders was missing a tiny crucial bit. Asked IWC if they could help...and of course they could.
Wear the O2K like this now. Perfect for sports, due to weight (not much), visibility (perfect) and size (see prior).
BTW, it´s ref. 3504, mid 1990ies according to the experts of this fine forum. Haven't had the case back opened.