The idea of this device is very interesting, imagine that you need to cut large branches that lie on the ground, and the tree falls into the grass or soil when pressed with a chain.
A nozzle made of metal is attached to the tire, it is mobile and resembles the lower jaw at the mouth with teeth. In fact, this is a bracket with two movable strips that are located on both sides of the chain.
Convenient crafts for work after winter, when the soil is soft from moisture, and under the tree is also a pillow from last year's grass and leaves.