These spacers are designed to prevent your weight plates from banging up against the mounting bolts on your plate storage pegs.
These fit storage pegs that measure 2" in diameter. This is the size used by Titan Fitness.
This model will fit very loose on the REP Fitness storage horns, and somewhat loose on Rogue Fitness products. I have other models that fit those brands.
These will also fit over a barbell. They can be used to space your plates away from your rack.
Be sure to measure your setup to see what size you need. If you need a size not listed, let me know and I can work with you.