I've had this keyboard for as long as I've had computers and took it apart recently to fix the dim NumLock light.
It is an interesting keyboard. It has no drainage holes and is lighter than the Model M, but has a steel plate reinforcing the keys and uses some sort of black slider underneath the key-cap to buckle the rubber domes when a key is pressed.
The sliders are rectangular with a rounded hole in the inside, black, and they aren't clicky. Does anyone here know what they could be?