It all started with personal shoe bags I have that don't fit any of my Salomons, Lowas, Vasques, Zamberlans or any of my chukka or desert boots. These easily fit up to a size 13 and some 14s.
Constructed out of 210D Ripstop Nylon (Coyote Brown, Black and Orange), dual #8 YKK reversible zippers, mesh and WooJin molded pulls. Plus a close cell foam padded base.
Photos show examples of selected boots and corresponding sizes of each pair.