POWERCOIL Thread repair kit UNC 1/4'' - 1/2''. The set includes a tap, an installation tool and a drill bit for each size, as well as threaded sleeves: 25 pcs UNC 1/4" x 20, 25 pcs UNC 5/16" x 18, 25 pcs UNC 3/8" x 16, 10 pcs UNC 7/16" x 14 and 10 pcs UNC 1/2" x 13.