Use to prevent rats accessingPrevents back flowEasy to fitWe now have the 4" plastic/clay barriers with Stainless Steel door. Unique push-fit non return valve giving instant rat and pest control in drains.The Rat Barrier was initially developed to help combat flooding problems in the UK but is now being used to prevent rodent ingress into buildings, both commercial and domestic. The valve is now used to prevent the following:Prevent Pest/Rodent Infestation Control noxious/Unpleasant Smells Prevent Back Flow/Flooding in sewers The perfect defence against rats etc entering via drains.A unique Non-Return Valve that easily push fit in to your current drainage pipework. An effective and low cost solution to prevent rats entering your drains from the local sewer and to stop flood backflows into your pipework. Can be fitted in minutes and does not require any specialist expertise or equipment. Can be locked closed to enable simple sealing off of a disused pipe run or to temporarily seal a pipe run whilst maintenance is in progress. We also offer standard Drain Plugs for maintenance use.4" for plastic pipes measures: 10.5cm end to end, with extension sleeve: 17.5cm.4" for clay pipes measures: 11cm end to end.6" for plastic pipes measures: 16.5cm end to end. Patented design. Manufactured and designed in the UK. * Please note the 6" model does not have a S/S door.