PMB90SHandheld metallographic polishing instrument,Pen style self-locking handle, rotational speed0-35000turn/Minute, adjustable speed, infinitely variable speed, forward and reverse switching, input voltageDC12VCan work continuously for up to12Hours, can be used for grinding and polishing metal materials and thin thin-walled boiler tubes, in conjunction with dedicated grinding heads on site3-5Quickly throw the mirror in minutes.