Universal circuit board with several white LEDs to fit in most of the passenger cars in the Märklin H0 program. One 73401 board is required for a short car (example: Langenschwalbach cars); two boards are required for long cars (example: UIC-x cars with a length of 28.2 cm / 11-1/8" length). Several of these circuit boards can be plugged together or a board can be shortened. Mounting hardware is included. Depending on the car type, the separate pickup shoe / ground spring set, item nos. 73404, 73405 or 73406 or the 72020 current conducting couplers with the 72050 ground spring is required for electrical connections.

The 73400 lighting kit (softer light for earlier eras) and the 73401 lighting kit (white light for more modern cars) are technically interchangeable.

A 73404, 73405 or 73406 pickup shoe / ground spring set or the 72020 current conducting couplers with the 72050 ground spring are also required for the 73401 lighting kit.