The quality of these drawer slides is terrible. Don't waste your time/money on this. I bought two pairs of kv 8400 28" rails. They arrived sealed in undamaged packaging. Upon checking them prior to installation, I found that each of the four rails was faulty. in several ways: 1) The black ones End stops/spacers seem to be broken so the guides keep popping out and falling out 2) The black ball bearing inserts keep falling out (possibly because of #1.3) One of the rails doesn't fully extend (or maybe the other three rails are fully extended) 4) The front corners of both rails are bent 5) The bags contain a few pieces of black plastic that appear to have snapped off the rails Several photos are attached documenting these issues After discovering the problem I contacted the manufacturer with these photos .After two days of no response I sent the KV slides back to Revain and bought the Promark slides (they si nd slightly more expensive but much better quality). . ) After 11 days I finally heard from the manufacturer who politely offered to replace some of the parts but not all of the goods. Not the best customer service. I will not buy anything from KV in the future.