Plastic Roofing Caps. Available in Clear, Black or Dark Grey. 6mm central hole. 20mm wide. 8.5mm height (cap open). 13mm height (cap closed). One-piece component. For use with a 5mm (10g) pan head wood screw or nail. Keeps the fastener protected from the elements. Manufactured in the UK. Please make your selection from the drop down menu. Image is for illustrative purposes. Free UK Delivery