24 A Double Check Valve Kit Consists Of Items 1)O Ring To Wabco Part No.523734 And Rdso Drg. No.Skdp 3031, Sl. No. 7 Qty. - 1 No/Set. 2)O Ring To Wabco Part No.523842 And To Rdso Drg. No.Skdp-3031, Sl. No.10 Qty. - 2 No./Set.