This is a DCC Concepts DCD-SA3-MD.3 Zen 3 Wire Medium Stay Alive for Zen Black and Blue+ Decoders (3 pack)

A set of 3 medium Stay-Alives with 3-wire connections to the decoder. Totally Plug and Play with Zen decoders.

Usable with Zen Black, Zen Blue+, Lenz and ESU or any decoder with three-wire connections for Stay-Alive.

Please note that connection of a DCC concepts Zen Stay-Alive to a non-DCC concepts decoder may invalidate your warranty, please check documentation which came with your decoder for details.