Features: Using 32-bit digital signal processing control technology, it is possible to set subdivision within 25600 and any multiple current values within the rate current. The use of builted-in segmentation technology greatly improves the smoothness and noise under low segmentation. Current setting can be freely selected between the rate values, and current automatically halves when at rest. Pulse response frequency can reach up to 250KHZ, and it have protections functions such as overvoltage, undervoltage, and short circuits. Driver integrates automatic parameters tuning function internally, which can automatically adjust the great operating parameters for different motors and maximizes the performances of the motors. Specifications: Materials: Plastic Size: about 14.2x9.7x5.3cm/5.59x3.82x2.09inch Power supply voltage: 30AC-80AC Working current: 2.1-8.4Amp Logics input current: 10mA Step time pulse corresponding frequency: 250KHZ Pulse low level time: 2.5US Package Includes: 1set Stepper Motor Controller note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to difference between different monitors, the picture may not reflect the actual color.