A forklift clips an upright a few times a year in almost every warehouse, the accessories on this page exist to make sure that impact hits a $50 guard instead of a structural column carrying a rated load. Column guards, rack guards, end-of-aisle barriers, and beam safety clips are the difference between a scuffed piece of steel and a rack that needs to be pulled from service and re-engineered.
None of these are structural upgrades to the system itself, they bolt onto or wrap around what you already have. That makes them the fastest, cheapest thing to add to an existing rack, whether it's a new install or a system that's been running for years without them.