I bought this kit to install some door locks and they're so cheap that they only give you ONE mandrel for two saw bits. The manual tells you to drill the 2 1/8" hole, then "disassemble 2 1/8" hole saw and assemble 1" hole saw". Yeah, good luck... once you drill with one of the saws, that mandrel stays in that saw bit and you won't be able to get it out even with your best wrenches. I'm stalled halfway into my door drilling and am returning this piece of Chinese made junk.