... ~99,999RPM 3-Contact Rotation speed: 0.5~19,999RPM PHOTO/CONTACT TACHOMETERSURFACE SPEED METER DT6236B 5 digits 18mm (0.6 ... data.Time Base: 6MHz Quartz crystalDetecting Distance: 50~500mmMeasuring Range:Photo Rotation speed: 2.5~99,999RPMContact Rotation speed: 0.5 ... ~19,999RPMSurface Speed: 0.05~1,999.9m/minResolution: Photo Rotation speed: 0.1RPM(2.5~999.9RPM) 1RPM(over ...