The Pass-through Check Valve (model 25969) can be used on the sides or back of flammable liquid safety cabinets. This unique system provides a means to dispense solvent through the wall of a cabinet. It can be installed either to dispense liquid into or dispense liquid out of the cabinet. Two ¼-in NPT threaded fittings (not included) are required to thread into both sides of the pass-through. Only install on the sides and back of the safety cabinet, never on the doors, bottom or top of a cabinet