DuPont Tyvek Wrap Caps are the recommended fastening method for DuPont Weatherization Systems. They provide additional protection around fastener penetrations and increases fastener-holding power. Wrap caps are easy to use. Wrap Cap staples feature a 1 inch diameter high density polyethylene with UV inhibitors cap that is engineered to distribute maximum holding power to the perimeter of the cap, reducing jobsite tear-offs. Wrap caps have strong holding power because of the larger surface area than a staple, preventing blow off of Tyvek wrap and builders need less fasteners per job. Warning: This product can expose you to chemicals which is [are] known to the State of California to cause cancer and birth defects or other reproductive harm.