... size, which make the Screw Supplier stable and easy to use. Features:Models: 514, 517, 520, 523, 526, ... work efficiency, 4 times faster than the circular type;3,Special detecting circuit, energy saving; 4,One ... stable and easy to use5,Various models for different type of screws like following. Models514517520523526530540suitablescrenws(mm)Φ1.4Φ1 ... Φ3.0Φ4.0 Stable and Easy Use Automatic Screw supplier