text: I don't usually recomend tools but this time I will. I had 70 holes to drill on the trailer 50 through 1 1/2" of wood then 1/4" of steel the others were all through steel. I machinist recomened I get bits made of cobalt steel. Well I ordered 5 11/32 drill bits hoping to get all the holes drilled. The first bit drilled 61 before getting dull so I am on the second bit. I do now recomend the cobalt steel drill bits