I specially took metabo wev 850-125 with bells and whistles when I was sanding a tree with it, I saw one of the features - as soon as the sanding pad literally barely bit on the side, it immediately turned on some kind of clutch inside, which cut off the motor from the disk, the motor spins, and disk is worth it. I thought, what nonsense, because it is so inconvenient to restart the grinder every time. I googled about the dudes who used saw blades on the grinder and how many fingers / arms / legs / necks and lives they cut, I became very pleased with my choice: speed control and super-reliable protection against biting - just generally cool. Doctors on the Internet write that there is nothing worse than a grinder from the inventory, most of all serious injuries.