1/2"-13 x 1-1/2" Hot Dip Galvanized Grade 2 / A307 Steel Coarse Thread Carriage Bolts 50PK A carriage bolt has a domed or countersunk head, and the shank is topped by a short square section under the head..
.A coupling nut is a long nut tapped from each side to meet in the middle, rather than all the way through in the same direction, used to connect two threaded rods end to end.