Manufacturer: TIMCO. Included Components: 1 x TIMco Sela Washers M8 x 28mm - (Bag 75) - 828SW. Washer type: Sela Washer. When using spring head roofing nails just a washer (SW) is required. If using hook bolts you will also require a Sela Cover (SC) to cover the washer and nut to complete the seal.