With the new CheckMaster 2 you can test any brand of servo for the pulse sent to the receiver, current-load and proper movement. It also has a very accurate optical tachometer to read out the RPM of running propeller or helicopter rotor blades. Specifications Servo Tester: ATV 10-100% Manual/Auto 900-1500-2100µs Prop RPM Tachometer: Up to 34000 RPM 1 to 6 blades 10 data memories Rotor Blade Tachometer: 800-4000 RPM 10 data memories Temperature Sensor: 0 to 120 degree C On-Board battery: NiMH 4.8V, 1000mAH Weight: 210g Dimensions: 113x80x28mm