The First Single Red Submariner: Reference 6538A

This is an ultra-rare (Milsub) Military Submariner, and to the best of my knowledge, it is the first Single-Red Rolex Submariner. Single-Red referring to the red depth rating located on the lower part of the dial. This watch also has the rare Big Winding Crown as well as the 3-6-9 Explorer dial, and the red upside-down pyramid at the top of the bezel insert — via Jake’s Rolex World