These bumpers do the job needed and that's to protect the seat and luggage rack from wear by the buckle! If you're getting straps with buckles be sure to add these to your shopping cart!
NRS Cam Buckle Bumpers
These buckle bumpers are solid! The seem well-made, fit the Green Chile buckles perfectly and without any loose play, and should do a good job protecting the more delicate surfaces. They're a bit pricey for what they are, but ultimately worth the extra, I think.
I use it with my watertight bags
They're a great idea, and no down side as they fit perfect and seem to do a good job of keeping the metal of the buckle away from anything under them.