Can be used in all spa systems that use a 12 Volt GE 912 bulb. Changes color at the touch of the button and can also color change phase every 30 seconds. Sundance compatibility details: All 2001+ Sundance, Portofino, Sweetwater Spas. All 650, 750 LX10, LX15 spa systems. All pre-2001 Sundance 850 spas with finger style circuit boards and Permaclear. These systems require the eprom change REV. 1.28K (6600-322) which will also alter the blower operation from 2 speed to 1 speed in pre-2001 models. It installs into the existing Bulb holder which must be accessed from the equipment area. Locate the back of the light, some models have a 1" PVC pipe sticking out of the light hole with the 2 wires for the light coming out. Unscrew the rear light bracket, install the new bulb in the place of the old bulb. Reattach the rear light bracket. Follow the instructions in the box to change the light logic on the PC Board if you have a dimmable light.