Fletching and nock weight are very critical for these lightweight A/C/C shafts. It is for this reason Easton designed the uni system. This innovative system allows the use of either Easton's light weight, high strength 1206 A/C/E nock or a standard plastic nock (with the uni system). The Uni Bushing allows for convenient and very precise nock alignment. The Uni Bushing can be installed with Easton #9040 hot melt adhesive. Dozen packs.