Tech Specs:

The W40 is a low-cost pin-screw terminal adapter. It can be used to convert the standard 0.1? lead spacing 20×2 pin headers to 40 screw terminals for easier field wiring.

The W40-P has a 20×2 pin-header for interfacing via flat ribbon cable. The W40S has a 20×2 socket for mounting directly on top of pin-headers.