McAlpine 1 1/4 BSP female inlet nut x 1 1/4 universal compression outlet wash hand basin space saver. Below the basin within the cabinet or furniture, the space saver has been designed to allow full use of the space. An internal membrane which opens under water pressure and then closes to form a seal and prevent foul odour and sewer gas entering the building but the water can flow freely. Without having to disassemble the the discharge pipework.