Pallet Rack Sump - Polyethylene Pallet Rack containment sump keeps dangerous and costly spills off floors, equipment and inventory. Allows direct forklift access to wooden pallet - sump unit stays positioned in the rack when removing pallet and drums. Low profile pallet rack sumps design fits into warehouse racking with minimal obstruction to adjacent storage areas. Unit holds up to (4) 55-gallon drums on a standard shipping pallet. Inside dimensions for a pallet are 49" x 49". Model PRS-51-D comes with drain/ball valve assembly for draining liquids.