The spring loaded clips are OK for 14 or 16 gauge wire. 12 gauge wire will just pull back out of the clips because it's too thick and the springs are pressed all the way back to fit the wire into the hole so there's less pressure on the wire. That's where these flex pins come in. Screw your 12 gauge wire into these flex pin connectors and slide them in. While they are thick as well, they are braided and allow the spring clips to grab and hold the flex pin tabs better. So they don't pull back out of the spring clip. Good clever product. The only thing I've noticed is that you might want to use some black vinyl tape to help insulate the flex pins from shorting against one another. There's not much room behind my setup. The leads looked like they might be touching one another so I put some black tape on the flex pin screw caps. They hold fine and my speakers sound great. If you're using heavier gauge wire or just want a secure grip of your wire in the spring clips use some of these flex pins.