The Bosch Speed Core system allows a standard SDS rotary hammer drill to drill core holes in concrete in diameters up to 4-3/8".  The new Bosch Speed Core system is a simple two piece design.  First, choose your SDS core in sizes ranging from 1" to 4-3/8".  Secondly, choose from a 13" extension or a 17" extension.  The 13" extension will allow you to drill at a depth of approximately 11" and the 17" will do about a 15" depth.  The shank includes a built in starter bit, no more loosing the starter pin in the hollow of a wall!  This system allows you to have one shank, and several SDS cores.

These long   SDS hammer drill bits are great for punching holes through concrete, block
and brick.  The sizes listed are over all sizes.  Typically your actual drill depth is 2" shorter.  Check
out the 9/16" bit , this the longest SDS bit Bosch makes.  Perfect for putting a couple cables
through the wall or use as a pilot hole and drill larger bit from either side.  These will work in any
Bosch, DeWalt, Hilti, Makita,  Black/Decker and Milwaukee SDS  hammer.