For use on twist or brad point drills to prevent excessive drill penetration
Positive depth control assures exact hole depths for multiple drilling jobs
Black oxide finish on cold rolled steel
Sizes included: 3/16-, 1/4-, 5/16-, 3/8-, 7/16-, 1/2-inch diameters
Includes hex wrench
http://www.amazon.com/General-Tools-Instruments-S838-Assortment/dp/B00004T7OI