The bar tensioner lets you adjust the chain tension of the Master Danila chainsaw: it moves the bar along the guides as the screw is turned.
Replace it if the thread is stripped, the gear teeth are broken, the plastic is cracked, or the chain does not hold its tension. A loose chain wears the bar and is dangerous, so it is better to replace a defective mechanism right away.
Before buying, check your saw model: for Chinese saws and their analogues, parts of different generations may differ, so rely on the marking and comparison with the old part.
