六角法兰自钻螺钉屋顶螺钉太阳能工厂standard stainless steel 304 tek screw hex flange self drilling screw roofing screw for solar.Solar steel hex head self-tapping screws can be used to solar roof hook or solar clamp to metal roof. Provides secure metal to metal fastening without the need to pre-drill and reduces cam-outs 1