BROKEN – Nidec Shimpo Contact Tachometer DT-107A-S12, 25000 RPM Max
We tested it with a known 1100 RPM motor and it read 7800 RPM using the 12″ wheel. However, you should consider this unit asBROKEN – FOR PARTS – AS IS. RPM Resolution 1 RPM. RPM Accuracy +/-0.006%.