Proxxon 28328 two-piece tungsten carbide Micro drills are 19/64-Inch x 1-1/2-Inch long, with a shank size of 7/64-Inch. Tungsten carbide Micro drills have ideal cutting angle of 6 Degrees. They are especially made for drilling glass, porcelain, ceramics, marble and they also do very well with semi precious and other hard stones. Made from top quality industrial Tungsten carbide material ground to provide very close tolerances.