if your door was originally outfitted with an old 5 inch acceptor, the 111 or 115 series will work fine. if your door is a standard 3 inch mech (like most mechanical coin mechs made by happ or coin controls) and you want to go electronic... you will need something like the 330 or the C120 which is a 3 inch acceptor. these will fit right in place of the mechanical mechanism.