Description: This 16550 which is the first explorer 2 to be housed with a sapphire crystal. It also houses the 3175 movement, shared with the fat lady GMT. Its number markers on the bezel are also much more bold and pronounced than its 16570 counterpart. Are we splitting hairs here? Likely but that is the exact reason why we collect these vintage watches. The case has likely been polished in the past but is extremely thick and even. The dial is very glossy and the lume has gone into a deep pumpkin color. This is a winner explorer for sure.