Fit into holes in the back of your reissue '51-'55 Precision Bass reissue body to anchor string ends. Nickel plated steel. Please note that most reissue '51 Precision Basses have the smaller size ferrule. Check the measurements carefully so that you order the type you need. I measured .550" overall, .628" barrel diameter and .751" at the upper lip, inside diameter .505". Brand New. Genuine Fender 0039425000. UPC 717669070649. Our current supply came from Fender as raw parts so no packaging. We only have two of these left so it is not a complete set.