1 . Closed design , putter to the top will not out.2 . Try to balance the top of the push rod , Can not withstand too much force.3 . In order to prevent the motor from burning out when turing , external drive plate or motor current limit is recommended.Motor Driver Technical Datae Dual Hbridge motor driver , can drive two DC motors or a 4wire twophase stepper motore.The module supply voltage 2V10V.Signal input voltage 1.87V.Single Operating urrent 1.5A current up to 2 5A , ow standby curent ( less than 0.1uA )Builtin common conduction circuit, when the input pin is left floating,the motor does not malfunctionBuiltin thermal circuit with hysteresis effects (TSD ),without worring about motor stallMotor Driver:Power positive and negative reversed will cause damage to the circuit .Output is shorted to ground or output short circuit , and the motor stall , the chip will heat protection , in the nearor exceeding 10V voltage and current is 2.5A situation can also cause chip burnedspecification:6Vcolour:yellowMaterial:Metal + plasticsize:11 x 2 x 2cmPackage Contents:1 * Model excavator arm1 * Motor drive boardOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is + 13cm.