Black Dowty Roofing Spat Corrugated Sealing Washer Twist Nail 6mm 8mm M6 M8 roof
Black plastic roofing washers - also known as SPAT washers. Also known as Spat Washers. to be used on corrugated roofing. The washers are designed to exert ever increasing sealing pressure at the washer rim whilst the fixing is being tightened.