Product description: High Quality 410 Stainless Steel, Stainless Steel with Superior Rust Resistant , More Solid and not Easy to Break; It is wood drill tail screw, mainly used in steel structure caigang watt fixed can also be used for fixing the simple construction of the sheet material; How to use? Self-Drilling Screws, eliminate the need for a pre-drilled hole. The length of the drill point determines the material thickness which the screw can reliably penetrate. When selecting a self-drilling screw design, it is important to consider the material thickness and type of materials to be . These stainless are great to use in environments that are damp; Modified Truss is extra wide with a low-profile dome and integral round washer, driver designed to prevent over-tightening. Specification size:4.2 * 13mm, 4.2 * 16mm, 4.2 * 19mm, 4.2 * 25mm, 4.2 * 32mm, 4.2 * 38mm:30 pcs each colour: silver Material: 410 stainless steel size: .2 Package Contents: 1 * set of Drilling Screws 2 * batches Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.