The 19661 design 2-quart collapsible canteen bladder was formed from ethylene-vinyl acetate copolymer (EVA) with the neck at one corner and measured approximately 7 x 7 x 3 inches. The EVA material was less susceptible to punctures than the vinyl film of its predecessor and its shaped design meant that it could be removed or inserted into the canteen cover when full.2 The bladder was either blow molded in one piece (Type I construction), or thermoformed from two sheets (Type II construction).3
1. Natick Labs Purchase Description LP/P Des 22-66 – 21st July 1966
2. Support To United States Army In Vietnam - Clothing & Equipment (United States Army Material Command Feb 1967)
3. Military Specification MIL-C-43603. (11 October 1968)