Thunder Group Bus tub in gray color is made of durable high density polyethylene and has 1 compartment with reinforced handles. Tub measuring 7 1/2″ x 21 3/4″ is stackable and freezer safe.. Polyethylene.7 1/2” H 21 3/4” W.Bus Box, 1-compartment, 7″ deep, reinforced handles, stackable, high density polyethylene, gray, NSF.NSF listed.. This bus tub from Thunder Group features Bus Box, 1-compartment, 7″ deep, reinforced handles, stackable, high density polyethylene, gray, NSF. It is made of Polyethylene. It is NSF listed.