Kundenbewertungen für VEVOR Diamantkernbohrmaschine Kernbohrgerät, 20 cm max. Bohrdurchmesser, Nass Trocken Hand-Diamantbohrer mit 4 Bohrern & 2 einstellbarer Drehzahlen (1000 / 2250 U/min) für Beton Ziegel Stein, 1500 W

While I usually like the value I get from Vevor products, this is different. There are two speeds when using this coring machine. When you start coring, it is best to start slow so the bit can start to bite into the concrete. Once the groove is established, you can speed up the process. On the slow setting, this machine still runs too fast. The coring bit starts jumping around, making this possibly dangerous. I am trying to send it back for a refund if possible. Vevor makes a lot of good products, and if they make one at a variable speed, I would try it, but you should pass on this one.

This would be a great drill and bit if only it was made for use in the USA. The plug is the kind used in Europe where it has 2 round pins and is meant to be plugged into a 220V outlet. It is utterly useless unless you plan to install this special kind of outlet. As a contractor moving from job to job, this is a complete loss. They don't really do returns. They offer a small sum and ask you to keep it. If you hold out long enough, they eventually refund all of your money.