20mm metal hole saw

I  bought this 20mm metal hole saw a few weeks ago because I need to drill a few holes through a sheet of metal. I had my doubts at first as the centre-piece was fastened to the shaft with an Allen bolt. I am going to be cutting through metal, I thought. What if the damn thing gives way? I needn’t have bothered with my fears. Just a couple of days back, I used it with great success. Worked a treat and I dare say, my fears were unfounded. Looks like I need to buy some other sizes too to add to my inventory of drill tools