Core bit extension</br>13-Inch extension?? SDS-plus</br>Screw core bit onto shank</br>Works with thin-wall core bits?? 1-1/2-Inch or larger</br></br>Product Description</br></br>Bosch SDS-plus thin-wall core bits are optimized for drilling with smaller hammers. Core body range is 1-Inch up to 4-3/8-Inch with a usable cutting depth of 3-Inch. Extension plus bit beyond 8-Inch should not exceed 600 RPM.</br><br/>http://www.amazon.com/gp/product/B00EMFOPB4