I had two 4” holes to drill though a twenty year old 5” concrete floor. A rental tool would have cost me 2/3 the price of the EDiamond 4” core drill and the 1/2 drill adaptor. That’s a no brainer for me. The core drill arrived two days after I ordered it from EDiamond and even with some shipping was a little less than the Amazon prime price. As some of the other reviewers suggested I cut a 4” hole though a 2x6 with a standard hole saw a then stood on the 2x6 to get the hole started. A small stream of water flowing on the coring bit kept it cool and flushed during the process. It took me less than an hour to core both holes and the bit still looks brand new. The 1/2 Milwaukee drill I used was probably a little underpowered for the job and got hot but with a few cool down breaks it worked fine. All in all I was very pleased with the core drill and the adaptor and highly recommend them.