Whelen 500 series Amber Modules Ballast. All LED's work. Require ballast to work. Tested on my liberty bar to make sure they work. Steady burn. Factory plugs were cut off. Sold as is.
These operate on 12 volts. In fact, I have seen some of them marked with "passive ballast" instead of "TIR ballast" on the label. While confusing on the surface, I imagine that this was meant to indicate that the lighthead has its own ballast on board, and does not require anything more than 12 volts to operate.
These are in fact ballast modules. The work on direct 12 volts but are not as bright as they should be compared to when they are ran off a ballast flasher.