With the experience gained through the beginning of the Vietnam War and the increasing use of covert and specialized military teams such as, the US Navy UDT/SEALs, US Navy EOD, US Navy Divers, Army Rangers, Green Berets, and CIA operatives, the Department of Defense determined that these specialists needed a more robust dive watch that would be purpose-built to meet the highest standards of the military and its operatives. As a result, the military wrote Mil-Spec MIL-W-50717, that specified the design details for the BENRUS Type I diving and field watch.
The two watches are very much the same design and profile. The reissue Benrus Type I has removable spring bars versus the original which are fixed. Also the bezel is aluminium vs the original which was bakelite.

Benrus Type I reissue 2020
Below is the original version.