Rubber Shower Head Pipe Hose Washers Gaskets Seals 1/2" BSP /0.5/ Half Inch / ½”. Replacement Shower Hose Connection Washers for 1/2" BSP threaded shower hoses (Standard UK fittings) Outer Width / Diameter 19mm Inner Width / Diameter 10mm (PLEASE NOTE that the inner diameter may vary +/- 1mm across batches) Thickness 2mm NOTE - The 1/2" refers to the shower hose size and not the actual rubber washer measurements. These fit all standard UK shower hose and shower head fittings. Read guidance on British Standard Pipe Thread (BSPT) measurements for the full background to this. In brief, they are known and referred to as 1/2" washers simply because they fit 1/2" pipe hoses.