They work under pressure or suction. Simple screwdriver adjustment. Various springs available.

可以工作在正压或负压下，简单的螺丝刀调节，多种弹簧可选。

youdao

They work under pressure or suction. Simple screwdriver adjustment. Various springs available.

可以工作在正压或负压下，简单的螺丝刀调节，多种弹簧可选。

youdao