Hoppers are perfectly balanced to roll forward when loaded and unlatched, and automatically return to upright locked position when empty McCULLOUGH Wright Medium-Duty Hoppers feature 2-1/2"W rockers, formed smooth top edge, and extended sides on pouring lip. -3/16" (7-gauge) sides with -1/4" base. Hoppers can be used with optional casters, with a forklift truck, or both.