The 041DJ001B is the receiver logic board for the LiftMaster 3800 and some other wall-mount openers made between 2005 and 2015. It's a 315MHz board with a purple learn button. No light socket on this one. Comes with the mounting plate so you're not hunting for hardware. If your wall-mount opener's not responding to remotes or the original board got fried, this is the replacement. You might find it referenced as 041DJ001, 041DJ001A, or 41DJ001 in the parts diagrams. Only for that specific model range and year though, so verify before you order.