Floplast OS17 black waste overlfow reducer fitting to join a 32mm pipe to a 21.5mm solvent weld waste pipe. This fitting reduces the amount of water flow to match the capacity of a 21.5mm pipe. Sturdy and reliable, this waste fitting provides a lightweight and cost-effective option. No expansion gap required on the solvent weld overflow system. Solvent weld joints in accordance with ABS/PVC-U waste systems fixing guide.