The flat top; the button top if it is longer can give problems for the closure of the cap
Flat top Molicel P42A’s ran perfect last month in Belize. Didn’t have a camera though, so so pics. Sofirn had a 5k version for a while (earlier last year) which I think I’d prefer. Still the 6.2k or so (estimated against other lights) version really looks great. Even on some daytime dives we used it in some caves and the colors “popped” nicely with a light at 70-90 ft. down (where everything looses color that deep). We also had the old SD-02 which was great too!
The lanyards are the weak point: have to get pro-level lanyards if you don’t want to loose the light (*AND have to stow it on the safety stop so you don’t tangle yourself coming out in rough water (*which Belize IS compared to other places we’ve dove). But it’s worth it for sure to ride the nurse sharks at Esmeralda, and spear hunt barracuda and lion fish- which are BOTH super tasty!