The original KM11 was two boards (W130 & W131) that was used in various PDP-11 computers and devices. They are used in the diagnosis of problems by being able to examine internal states that are not normally visable on the front panel.
The replica KM11 is a single board that is plugged into an extender board which is plugged into the appropriate slot(s) in a PDP-11. Full documentation is provided including schematics and parts lists.
Other people have created replica KM11 boards. One is from Tom Uban. His design (and part of this design) is based upon work by Tony Duell.
A light mask is available that is used to shield the light from the LEDs from each other. It also serves as a good mount for any overlays that might be used. It is machined from a solid piece of Delrin plastic for strength and durability. Mounting holes are drilled and tapped for 4/40 machine screws. When ordered all mounting hardware and spacers are supplied.
Available seperately is an overlay for the RX01 and a set of 2 for the RK11-C.