21-HWM-5 PACK is a circuit board with a NEM660 (MTC21) socket with solder pads to connect wires. The male 21-pin socket may be used to plug into a 21-pin decoder such as the WOW121 or EU621. The decoder can then be hardwired or used with a plug-in harness. The 21-HWM is great for situations where space is limited and a full-size motherboard cannot be used. A pin-out of the 21 pins can be found Here.
To solder wires to the provided pads simply: