These are simple sleeves for mounting your resistance bands. They allow you to perfectly space your plates so that they don't interfere with the bands or cause an uneven side-to-side weight distribution. They can also space your plates away from the center so you don't smack your rack when unracking.
The flat part will accommodate a band that is approximately 2.25" wide. If you would like a custom size, leave a request in the comments and I'll see if I can do that!
Sold as a pair.