1. The same two locking T nuts screw with a bolt, attach a tightening torque between two nut, bolt connection is reliable.The second is a dedicated locknut, need and a locking washers are used together.Dedicated locknut is not hexagonal nut, but a round nut, the nut on the circumference of a circle with three, four, six or eight gap (depending on the size of nut and manufacturers products vary), these a few gap is the focus of tightening tools, and locking washers bayonet card into place. 2. Within the cylindrical surface of the locking t nuts to round thread runs through the thread hole is drilled surface (usually 2, outer circle like 90 distribution), used to screw into the small diameter countersunk head screws, the purpose is to put a thread under direction of the centripetal force, prevent loosen lock nut.Sales on the market at present the quality of a good lock nut on the nut of the inner circle surface with consistent with the lock nut thread copper pieces, used to avoid the radial head screw direct contact with the locked thread and damage to the latter.