The space saving WHB-1 wash basin features McAlpine's self-closing waste valve. This valve allows air to be drawn into the discharge waste pipe when negative pressure is present, eliminating the need to re-vent the discharge piping. This provides greater flexibility in piping design. Specifications:- Size: 1 1/2 BSP female inlet nut x 1 1/4' universal compression outlet;- Designed to make the most of space under the basin inside a cabinet or furniture;- Internal membrane opens under water pressure, allowing the discharge to flow freely, then closes to create a seal, preventing foul odors or sewer gases from entering the building;- This valve allows air to be drawn into the discharge waste pipe when negative pressure is present, eliminating the need to re-vent the discharge piping. This provides greater flexibility in piping design;- The valve can be easily cleaned without disassembling the discharge piping. Simply remove the cotter pin on the front of the valve, remove the plug and membrane, and wash in hot soapy water. Reassemble and reposition the cotter pin in the slot provided - The WHB-1 Self Cleaning Wastewater Valve has no water seal and therefore will not dry out from evaporation or lack of use as the membrane seal remains closed - Overall height 62 mm.