The part number 51218 is a Balboa Water Group topside control panel (specifically a 2-button Duplex auxiliary panel ).
Many hot tub manufacturers that use Balboa control systems have incorporated this panel into their spas over the years.
Manufacturers that use or have used the Balboa 51218 topside panel include:
Jacuzzi: Used in certain models and also listed as a remote panel for Jacuzzi.
Emerald Spas: This specific panel is compatible with some Emerald Spa systems.
Caldera Spas: This topside is used in certain Caldera spas.
Cal Spas: Known to incorporate various Balboa components into their hot tubs.
Master Spas: This manufacturer utilizes a variety of Balboa control systems in many of its models.
Coast Spas: A Canadian manufacturer that often includes Balboa components in its hot tubs.
Marquis Spas: Incorporates Balboa control systems into some of their spas.
Platinum Spas / Superior Spas: These brands frequently use Balboa equipment and parts in their spas.
BullFrog Spas: Uses Balboa electronics as a primary component in their spas.
This topside is an analog Duplex panel designed for use with specific older Balboa circuit boards (such as 50803 and 51230), connecting via an RJ45, 6-wire "phone plug" style connector. The panel typically comes without an overlay (the label sticker for the buttons), which must be ordered separately to match the specific spa's functionality.
