26C508 up for sale is a large twist on gas or fuel tank dust cap , covered under NMC Wollard Inc 41768 and also deluxe tank mfg 961248 and also military NSN 5340-01-492-5867 , this cap has a major outer diameter of 4 5/8 inch the area that twist onto the tank with the three locking tabs is just over 3 1/2 inches , has a chain and a retainer ring included , comes in a sealed bag with the military  tag on the front as shown in the photos , also see our store for more items like this we add new items each week , thank you rwk