A Bugle Batten Screw -countersunk head and internal hex drive. They are a heavy duty fastener which come in various lengths starting at 50mm and are all 14g (7mm) thick. Manufactured with ribs under the head to drive them straight in and will cut the countersink themselves. The head is shaped as a bugle head , the idea being the bugle form wont promote timber splitting as it countersinks due to the fairly shallow change in angle.
Applications include Fixing roof battens to timber rafters, fastenings heavy timber needing flush smooth finish, fencing, decking, pergolas and stock-yards.