Hand winding
Rare one-piece case,embedded Lugs with spring bars
H3 with radiation symbol dial
Case back engraved:
WATCH, WRIST: GENERAL PURPOSE
DSA-400-74-D-0273
BENRUS JULY 1975
MIL-W-46374 A
DISPOSE-RAD-WASTE
6645-00-952-3767 U.S. MFG. PART NO. 179 Q