1 1/2" Spare Syphon Backnut High-quality plastic component Easy and simple use kit 1 1/2" Spare Syphon BacknutA great range of easy to install spares is available, these is suitable for a variety of installations, including both domestic and commercial applications. This selection of syphon backnut includes the most popular replacement mechanisms that are required to fix or replace damaged parts of your toilet flushing mechanism. Features This securing nut is recommended for use with flush valves and siphons with 1 1/2" outlets. It offers reduced flush for water-saving benefits It has an easy to remove upper section allowing for easy maintenance. Replacement securing nuts for 1.1/2 inch BSP outlet push button flush valves and lever-operated syphons.