ZI EA Factory is specialized in carriage bolts manufacturing.

Carriage bolts, mushroom head bolts, round head square neck bolts or 

coach bolts are the bolts used to fasten wood to wood or metal to wood.

Generally, people use carriage bolts for security fixings, such as docks, 

outdoor decks, locks and hinges, where the bolts must only be removable 

from one side. 

The design of the round head and square neck prevents the carriage bolts from 

being unlocked from the insecure side.