Do you do your back squats, front squats, push presses, etc. from a rack or rig? If so, you may be familiar with the term "J-Cup."
Those that aren't familiar, a J-Cup is a laser cut piece of steel that is bent into a "J" shape. The purpose of a J-Cup is to hold a barbell on a rack or rig, and they are easily adjustable based on the height of the individual. They come in various sizes, but not all feature inserts on the steel to protect your bar's knurling.
What you absolutely don't want is your barbell rolling and grinding around on steel, which is what the picture to the right is showing. Many of the new J-Cups feature a plastic insert that helps prevent knurling damage, so these certainly would help. If you don't have this protection keep reading.
As mentioned before, many of the newer J-Cups have plastic inserts to help protect, however there are plenty of bare steel/powder coated J-Cups out there.
One extremely easy, cost effective way to protect your barbell's knurling and finish is to add padding to the J-Cup. This can be done using various materials and techniques. As shown here, this gym owner decided to take some rubber mat scraps and secure it with some duct tape. Super easy. Some simple other techniques that we've experimented with are towels, t-shirts or even duct tape. The bottom line: you need to have some sort of padding to protect your knurling and finish. The last thing you want is a smooth knurling when taking a snatch or a scratched finish exposing it to the risk of rust.