This product is No Longer Available.
M&S no longer manufacturers the MC602. You can replace only the master station by using the M&S DMC3-4 master, DMC1H housing, and DMCFM frame (so there is no drywall patch or repair).
The other option is to replace the entire MC602 system with a DMC3-4 retrofit kit, or an Intrasonic RETRO kit.