... 999RPMContact Tach: 0.5~19,999RPMSurface Speed: 0.05~1,999.9(m/min)Resolution: Photo Tach: 0.01RPM(2.5 ... ~999.99RPM) 0.1RPM(1,000~9,999.9RPM) 1RPM(over 10,000RPM) Contact Tach ... : 0.01RPM(0.5~999.99RPM) 0.1RPM(1 ... ,000~9,999.9RPM) 1RPM(over 10,000RPM) Surface ...