Wire Cage Clips by Pet Lodge

Pair these with wire clip pliers to affix wire pieces together. I use these clips to connect welded wire to cattle panels or to run invisible fence along my field fence.

From the supplier:

These handy metal clips are designed for assembling or repairing 14 to 16 gauge wire panels for rabbit hutches, pet homes, and other wire products. The ferrule type clips wrap around wire or other material to fasten it together. Great for many uses around the farm, home, and shop. This package contains enough clips to assemble three to four average-size wire units. 1lb Bag.