Hopper automatically dumps when bumper release contacts the front of the dumpster. Hopper returns to an upright and locked position automatically after it dumps. Also includes a cable that may be operated from the seat of the fork truck to manually dump the hopper. A safety restraint is provided to secure the hopper to the fork truck. Usable fork pockets are 7-1/2"W x 2-1/2"H. Self-dumping hoppers facilitate compliance with OSHA General Industry rule 29 CFR 1910.178(m)(5)(iii) by allowing lift truck operators to remain at the controls of their truck throughout the dumping process. Optional leak proof design sold separately. D-25, D-33, D-50, D-75, and D-100 are stackable if you stack the top hopper turned 90 degrees from the bottom. Blue baked-in powder-coated toughness is standard. Must be attached to fork truck when dumping.