Needed new rock guards for my NH 451 sickle bar mower so I bought these cheaper parts instead of expensive NH parts. Bolted in great. A few didn't seem to align well with the knives leaving a pretty wide gap between knife and guard. Internet said you could slide a pipe over the guard and bend it, but some said that they would break. I called TSC customer support and the rep had no idea what I was talking about. Said she would contact the product buyer and they would get back. Never heard from anyone. Ended up removing problem guards and grinding the mounting surface with a slight taper to align them. I think parts were OK, but Tractor Supply Customer Service was a failure.