To combat the alarming number of foot fungus disease cases among US troops operating in The Plain of Reeds and Mekong Delta, USARV requested 400 specially designed combat boots to help with foot hygiene of the 9th Infantry Division. on 16 Oct. 1967. The division surgeon visited Natick Laboratories at the end of Oct., and on 17 Nov. 1967, Army Material Command was directed to purchase 400 test boots under ENSURE priorities. These were air expressed to Vietnam on 5 Jan. 1968, but proved unsatisfactory. Further action on this design was cancelled 18 Nov. 1968.(as per Stanton "US Army Uniforms of the Vietnam War" pp 138-139.
This pair came from the estate of USAF Brigadier General Olbert F. Lassiter. I've had these about 35 years.