PRO Compact Dual Flush Toilet Syphon in 9-inch size manufactured by Fluidmaster. This PROSY090 WC flushing syphon for toilet tank comes with variable flush volumes, internal overflow and leak-free component as well as 2.5\" C-link. The toilet syphon is suitable for the majority of lever operated toilet cisterns with 1 1/2\" BSP toilet cistern outlet connections. This toilet syphon replacement unit is fully WRAS approved and has an internal overflow protection system and anti-leakage components. The 9-inch dual flush syphon has variable nominal full flush volumes from 6 litres to 9 litres and partial (\"half\") flush by holding the toilet cistern lever down until the flush is complete. The overall dimensions of the WC syphon are: 270 mm height (from the top to the start of the cistern thread connection), 190 mm width, 95 mm depth. Main benefits of Fluidmaster Dual Flush Toilet Syphon Compact PRO series: - Variable flush volumes; - Capable of full and partial flush; - Internal overflow; - Compact design fits even modern smaller cisterns. How the dual flush function of this syphon works. The full flush volume is achieved by flushing the WC in the normal way by fully depressing the lever and immediately releasing once the flush has started. The short flush volume is achieved by fully depressing the handle in the normal way and holding the handle in the depressed position until the flush cycle is complete. Internal Overflow Should the unlikely occur that your fill valve sticks open, all syphon's have an internal overflow capable of coping with up to 35 l/min of excess water. As the water level rises, so does the water level inside the syphon, until it reaches the \"Spillover\" point. At this point the water inside the syphon will run down the down leg and into the pan, preventing any further rise in water height inside the cistern. When selecting a syphon, ensure that the bottom of the coloured shroud (the “Spillover” point, point P) is lower than any existing outlet point inside the cistern i.e. lever handle / side lever / side inlet internal overflow and cistern rim. Fitting the PRO series dual flush syphon: STEP 1 Pre-Installation 1. Turn off the water supply to the cistern and remove the cistern lid. 2. While still full, mark the normal water level on the inside of the cistern. 3. Flush the cistern and remove any remaining water with a sponge or cloth. 4. Disconnect the \"C\" link from the flush lever and save for re-use if required. 5. Remove the old syphon. STEP 2 Fitting the syphon For high and low level cisterns 1. Undo the coupling nut underneath the cistern and loosen the syphon back nut. 2. Remove the old syphon unit from the cistern and fit the new syphon ensuring that the rubber washer is on the inside of the cistern. 3. Hand tighten the back nut and tighten a further quarter turn with suitable grips. 4. Re-fit the \"C\" link. 5. Re-fit the flush pipe sealing washer and coupling nut. For close coupled cisterns 1. Disconnect the water supply from the fill valve tail pipe. 2. Loosen the wing nuts on the back of the WC pan, loosen the wall fixing screws inside the cistern. 3. Carefully lift the cistern from the WC pan. 4. Remove the large \"doughnut\" shaped washer and then loosen the syphon back nut. 5. Remove the old syphon unit from the cistern, during which it may be necessary to remove some or all of the fill valve unit. 6. Fit the new syphon into the cistern ensuring that the rubber washer is on the inside of the cistern. 7. Hand tighten the back nut and tighten a further quarter turn with suitable grips. 8. Place a new doughnut washer onto the thread and carefully re-fit the cistern onto the WC pan. 9. Re-fit the wall fixing screws and wing nuts. 10. Re-fit the \"C\" link. 11. Re-connect the water supply to the fill valve.