SHANS stainless steel self-tapping wire is made of 401 stainless steel. The material is hard. It can be widely used in wood, PVC, galvanized steel pipe, and even can penetrate steel bars. It is an ideal accessory for installing lock channel in greenhouses, no matter if it is iron or aluminum alloy greenhouse lock channel, there is no need to drill holes in advance. Friendly reminder: Avoid using an impact wrench, or an impact driver. These screws are very hard and therefore more brittle. Vibration from an impact wrench can damage these screws.