The 18-8 stainless steel carriage bolt with plain finish has a square neck with round head and meets American Society of Mechanical Engineers ASME B18.5 and ASTM F593 specifications. The 18-8 stainless steel material provides strength and offers good corrosion resistance in many environments. The material may be slightly magnetic. The square neck prevents the bolt from turning once installed, even when a nut is tightened. The round head has a domed shape.

Carriage bolts, also called round head square neck bolts, are square-necked threaded fasteners commonly used in wood fastening applications. The bolts square neck prevents it from turning once installed using a nut.