A screw is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder,it is an externally threaded fastener capable of being inserted into holes in assembled parts, of mating with a preformed internal thread or forming its own thread
The common screw we mention has thread form which prohibits assembly with a nut having a straight thread of multiple pitch length such as wood screws, tapping screws..
The screws which topkun can suppy are mainly including Self-drilling Screw,Self-tapping Screw,Dry-wall Screw,Chipboard Screw,Wood Screw,Machine Screw,SEMS screw.and these screws are widely used for Metal Building , Mechanical Equipment, Automobile, Home decoration etc.