The lower knife is the main component and is what makes the sewing machine an overlock in the first place, because in combination with the upper knife it enables the precise cutting of the fabric and is jointly responsible for the fast and precise operation of the machine. If the upper knife has been deactivated, the lower knife is also without function. Always make sure that the blade is sharp.
The knife is suitable for the SL3335, SL3487 overlock machines.
