The FIX-A-TAP washer kit is suitable for 38/40mm traps. It includes 2 square-edged washers and 1 double tapered washer. The double tapered washer is a thicker type used to seal off reverse bends in pipes. Squeeze firmly when using this style of the washer. The 38mm trap washer can be used for fixing leaks coming from the traps in bathroom or kitchen sets.