External Wall Insulation Fasteners are used to fasten heavier insulation materials to surfaces that self-sticking pins cannot adhere to. Each base is perforated with 44 small holes that are used to "grab" the adhesive or allow a screw/nail to hold the base in place. Once the insulation is pierced onto the pin, a locking washer or a domed cap can be installed to hold the insulation in place.