This is from the permit application on the mvc website:
(
http://www.state.nj.us/mvc/pdf/About/BLC-54C.pdf)
MOUNTING OF LIGHTS; CANDLEPOWER:
No more than two blue lights may be installed on a vehicle. If one light is used, it shall be mounted on the center of the roof; the left windshield column; or the front of the vehicle so that the top of the light is no higher than the top of the vehicle’s headlights. If two blue lights are used, they shall be mounted on either side of the roof at the front of the vehicle directly behind the top of the windshield or on each windshield column.
The blue lights shall be temporarily attached, removable lights of the flashing or revolving type, and shall not exceed seven and one-half inches in diameter. The lights shall have a blue lens and shall be equipped with a lamp of not more than 51 candlepower as measured without a lens. The lights shall be controlled by a switch installed inside the vehicle.
ALTERNATING FLASHING OR STROBE HEADLIGHTS ARE PROHIBITED AND SHALL NOT BE INCORPORATED INTO THE HOUSING OF ANY LIGHTING.