... 7/8" to 26" , normal sizes consist of 5 7/8", 6", 6 1/2", 7 1/2", 8 1/2", 9 1/2", 9 5/8", 9 7/8", 12 1/4",13 5/8 ... ", 14 3/4", 15 1 ... /2", 16", 17 1 ... bearing or roller non-sealed bearing.4.Used for mining, hydrology, subterranean ... . 3 7/8''Steel Tooth Bit