Set of 3 bits for drilling holes in glass without chipping or cracking because they are made with a hole (core) down the middle of the bit, especially for glass. These bits are perfect for drilling jewelry, windchimes etc. without chipping or cracking the glass. Included in the 3 piece set is: 1/16" (1.55mm) bit, 5/64" (2.05mm) and 1/8" (3.15mm). Remember to ALWAYS use water when drilling.