STINGER 3/8 In. x 3/8 In. A-11 staples are for use with the STINGER HT38 Hammer Tacker to install roofing felt and rolled insulation. The 21ga 3/8 In. crown staples are 3/8 In. long, meet ASTM F1667 requirements, and feature A-11 galvanized chisel points.