Contains 2 rubber duckbill check valves for VacuFlush vacuum and discharge pumps. Fits pump models: S12DM, S12DAB, S24D, S32D, S115A, S12, S24, S32, T12, T24, T32, VG12, VG24, & VHT. (All S and VG pumps require four duckbill valves).