Repair kit for Centek 2 in. exhaust thru hulls with externally mounted rubber flapper. 2 in. Thru Hull Flapper Repair Kit | Centek 1200344 Replacement exhaust thru hull flapper Inlcudes rubber flapper and 2 mounting screws Exclusively for Centek 2 in. exhaust thru hulls with flappers - not for other makes