205 Pcs Self Tapping Screws for Metal,M4.2x13~50mm Self Drilling Head Sheet Tek
How to choose the size ?. : Match screw length to material thickness,7 sizes: M4.2x13/16/19/25/32/38/50mm. e.g., 13-16-19mm screws for 1.5-3mm steel plates??. 25-32-38mm screws for 3-6mm steel plates??.