The T13 was designed by OSS and manufactured by Eastman Kodak. It was designed to be easily usable with minimal training. The size and weight of a baseball, it weighed about 340 grams with 255 grams of explosive filling. To use, the grenade is held with two fingers over the fuse plate. The pin is pulled and the grenade is thrown. Once in the air, the fuse plate detached and un-spooled a wire, arming the impact fuse.