High -strength, high -plastic aluminum alloy boxes greatly improve the product strength while maintaining lightweight self -weight. Two -level transmission and short handle make the operation more laborious. A 360 ° rotating handle provides a variety of operations in a limited space. The sprocketing mechanism that can rotate freely on the empty gear ensures that the chain can pass quickly and lightly. The fully closed and automatic braking system effectively eliminates the impact while keeping the brake clean and dry, making the work safer and reliable. Can control the weight of the weight micro -control.