Hillman Fasteners 240204 Carriage Bolt, 3/8-16 x 8'', 50 PackSteel round head, square neck, coarse thread. Pack of 50. 3 8 16 x 8'' Carriage bolt Steel round head Square neck Coarse thread 50 Pack. Warning: Fuels used in liquefied propane gas appliances, and the products of combustion of such fuel, can expose you to chemicals including benzene, which is known to the State of California to cause cancer and cause birth defects or other reproductive harm. For more information go to www. P65Warnings. ca. gov