Use with Core Bit 48-20-5140 and Center Pin 48-20-5199 for starting a 1-1/4 inch hole. After drilling to a depth of approximately 1/4 inch, stop hammer, remove guide plate and center pin, place core bit back into the grooved area and resume drilling to required depth of hole.FEATURES: 2-1/2 in. diameter. Plastic. Used with core bit 48-20-5140. For bit stability - reduces bit walk