Armycrew Ripstop Tear Resistant Cotton Jungle Boonie Cap with Chin Strap. 100% Cotton. Classic military style cotton ripstop fabric boonie hat for men. 2 ventilation holes featured on each side of hat. Flexible, packable, breathable and crushable. Resistant to tearing and ripping with a special reinforcing technique. Available in 4 sizes; S, M, L, XL with adjustable chin strap.