In March 1968 U.S. Army Vietnam (USARV) asked Natick Labs to produce a version of the Tropical Combat Uniform with improved mosquito protection. After testing various fabrics in Florida, Natick selected a 6.5oz nylon-cotton material that was also more tightly woven than the standard fabric. This provided 98% protection from mosquito bites, though the weave did inhibit airflow.1 4,500 of the experimental uniforms were sent to Vietnam for evaluation in June 1969. However, after a poorly conducted test USARV reported that the uniform was uncomfortable to wear and consequently it was not adopted.2
The design of the Mosquito Resistant Tropical Combat Jacket was identical to the 5th pattern jungle jacket, having a back yoke, only one pen pocket and no sleeve gussets.
1. The standard Tropical Combat Uniform allegedly provided 92% protection from mosquito bites.
2. Stanton, U.S. Army Uniforms of the Vietnam War, pp 6