BigHead® Collars consist of an internally threaded collar welded to a large perforated head. Standard collar lengths range from 5-22 mm, and standard heads range in size from 19-58 mm across. They are available in several different standard head shapes, to suit your specific application needs, with or without a sighted center hole and customized shapes and sizes are readily available. Their large perforated "head" provides an invisible, molded-in fastener, fixed for life, with very high torque and shear resistance. These fasteners are made from mild steel or stainless steel.