Harness pads
If you have a competition-style seat belt setup with 3 in. shoulder belts, then you'll want these RJS harness pads.
They're available in several colors and slip neatly onto the belts for an easy installation and a professional look.
The important thing, though, is that they help to cushion any impacts in the event of a crash.
An extra-added benefit is that they protect your driver suit from abrasion.