These bits are a very popular type and size used by Jewelry Designers for drilling a nice clean hole in Beach Sea Glass for making Earrings, Pendents and Bracelets. They have multiple layers of industrial diamond particles bonded to the tips which provides for longer drill life and are excellent for drilling completely through any thickness of Beach Sea Glass up to 1/2" thick. These Bits can be used in any high speed Dremel-Type Rotary Tool or Small Precision Drill Press with a 3/32" collet or adjustable collet.