Strong, somewhat flexible plastic. They are just big enough so that the cable is held in place, but can still slide around a little. Easy to use and secure.

There are little nubs inside the u that slightly grab the cable! It fits snugly and remains taut. Fits cat5e cable great. Fit rj-45 cable3.

It still works on cat 6 wire but may be too small for coax. They're very small and discreet. Nice accessory to complement electronic install. Ethernet.

Nails are too short. Would not even hold on wood siding. Probably worse with drywall. Looks as though the lid fell off before the item was packaged. The clip is too short to attach to the wall.