These are TIMCO’s self-drilling composite panel screws, for fixing composite (sandwich) panel to light section steel up to 5mm. The self-drilling point cuts its own hole through the steel with no pre-drilling, and the split thread keeps the fixing steady through the thick panel. The hex head drives with an 8mm socket and the EPDM washer seals the hole against the weather. The exterior coating stands up outdoors on insulated roof and wall panel.