A double-sq. screw head is commonly made use of on industrial-amount designs as well as haulmark trailers. A bulged head, in some cases with a black phosphate coating. perfect for attaching drywall to some metal stud https://donnauwsg341224.blogginaway.com/30217762/how-much-you-need-to-expect-you-ll-pay-for-a-good-types-of-screw-heads