These switches fit the PLAY / PAUSE & CUE positions on :-

CDJ2000 / CDJ2000NXS / CDJ2000NXS2/ CDJ850 / CDJ900 / CDJ900NXS / CDJ400 / CDJ350 / XDJ700 / XDJ1000 / XDJ-RX / XDJ-AERO / DDJ-ERGO / DDJ-RR / DDJ-RX / DDJ-SB / DDJ-SB2 / DDJ-SB3 / DDJ-SR2 / DDJ-S1 / DDJ-SZ / DDJ-T1 / MEP-7000 / SEP-C1

The switches are supplied singularly but usually changed as a pair.