Before using them, it's important to ensure that the coupler you choose fits the NEM pocket.
Conversion NEM pockets for Hornby, Dapol and Airfix (2 pairs) GVH NEM03
Conversion NEM pockets for Bachmann, Hornby, Tri-Ang (2 pairs) GVH NEM01
GVNEM01 Conversion NEM Pockets For Bachmann, Hornby, Tri-ang (2 Pairs)