BT43Semi-automatic Backlatch system for Overlock machines like AZ8020SD-8 adn AZ7020/7120SD-8 class.New back tack device with movable stitch tongue to solve the several problems with BT13 which, has no stitch tongue. It is easier to clean the movable tongue of BT43 to minimize malfunction of the stitch tongue caused by accumulated lint. Improved chain cutter shortened the length of chain into the seam while making the operation smoother. The chain cutter can be removed with one screw while keeping engagement of knife for easy maintenance.
