The combination of the disc spring, the inner roller and the chuck provides a good balance of opening and closing of the mold. 

The rotation of the roller can better prevent the occurrence of eccentric 

wear, and the locking sleeve is symmetrical up and down, so if it is 

worn, it can be installed to be used again,

because the back of the locking seat has a vacant position, 

so when there is a step on the template, it’s still good to use