Drilling into frames filled with concrete can be a nightmare on drill bits. Once the drill bit starts spinning around in concrete it’s immediately ready for the garbage. Concrete is composed of sand. Sharp edged drill bits spinning at high rpm in hardened concrete is the equivalent of sandblasting. This is why they become dull or smooth after hitting concrete. Instead of ruining expensive drill bits, use this Specialty Drill-N-Tap KIT for drilling and threading holes to attach closer arms OR CONTINUOUS HINGES to grout filled frames. Comes with (100) Hex Head DRILLERZ to drill holes and (100) Hex Head TAPPERZ to THREAD holes. EACH will drill or thread at least 5 or 6 holes in grouted frames. That's MORE than the number of holes needed for typical closer arm installation. For example: If you have to attach a closer arm to a grout filled metal frame using a 1/4-20 screw...Simply Drill holes for closer arm in frame with #14 HEX HEAD DRILLER. ONE screw will make about 5 or 6 holes. This steps makes 1/4” holes and clears out concrete approx. 1 inch deep. If Door Closer is supplied with MACHINE SCREW...Apply Burthas ButtWax to 1/4-20 Self Drilling HEX HEAD TAPPER then thread holes. ONE screw will thread about 5 or 6 holes. Apply Burthas ButtWax to Machine Screw and install. If Door Closer is supplied with Self Drilling screws...Apply Burthas ButtWax to Self Drilling Screws and install. THE SAME STEPS CAN BE USED TO DRILL and THREAD HOLES FOR CONTINUOUS HINGES that uses 12-24 screws ! Using #12 Drillerz to drill and clear holes then use the 12-24 Tapperz to thread holes. It's like having 100 Drill Bits and Tap SETS ! Kits available for: #14 with 1/4-20 #12 with 12-24 #10 with 10-24 Each Drill-n-Tap KIT INCLUDES : 100 Hex Head DRILLERZ for Drilling Holes. 100 Hex Head TAPPERZ for Threading Holes. 8 oz Burthas ButtWax for Smoother Drilling Tapping & Screwing. Nutsetters for Hex Heads ARE INCLUDED !! BIG TIME AND MONEY SAVER