MC-1"-21, MC-3.5"-21, and the MC-5"-21 are harnesses with wires connecting a 7-Pin JST to NEM21 socket.
T-1"-21, T-3.5"-21, and the T-5"-21 are harnesses with wires connecting a 9-Pin JST to NEM21 socket.
21-HW-5PACK is a circuit board with a NEM21 socket with solder pads to connect wires to the NEM21
To solder wires to the provided pads simply:
1. Tin each pad with a SMALL amount of solder
2. Strip the end of each wire and tin it with a small amount of solder
3. Solder the wires in order from top to bottom as listed:Green