This attachment saved me a lot of headaches. I installed an electrical repair box that required drilling a hole through a bolt to power an outlet from another box. The bolt was hidden behind drywall and buried about 10 inches from the cutout for the new box. I used a 16" long, 3/4" drill bit for this and at the very end of the cut the guide tooth broke. and fell into the pen. No drilling with a drill could loosen this metal tooth (broken drills are not meant to cut metal :). What was the decision to remove the metal tooth and finish the hole? THIS IS A DRILL. This bit went into a 12" extension that cut through a metal tooth and made a hole in about 1 second. Saved me a big headache! Thank you Bosch!