I used 3/8" nylon slugs with rockers, lasted one season, the edges of the mast track wears through the nylon pretty quicly, the rockers also tend to get stuck at the mast gate plates. The broken slugs were temporarily replaced with stainless steel with rocker, I intend to replace all with stainless steel without the rocker, best buy at:
http://www.sailrite.com/Slug-Bail-Without-Rocker-3-8?sc=2&category=98
