the package will provide you with 6 pieces of directional vent valves, each vent filter is equipped with an o shaped ring, compatible with filter C100, C250, C500, C750, extended cycle DE filter EC30 and EC40 series, EC50A/ AC series featuring fine workmanship, the air release valves are strong and sturdy; The surface and thread edge of the pool filter are and round, easy to use, will not be stuck the valve pool filters are mainly applicable for pool, sink, spa filters or other equipments to exhaust air before operating, pool filter air relief valves can make the system work well and give you a better experience Colour:black Material:plastic Package Contents: 6 x Directional Vent Valve Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.