Automatic Locking Pliers

What are Locking pliers? They are pliers that can be locked using an over-center toggle action into position. One side of the handle includes a bolt used to adjust the space between jaws, the other side of the handle ( in larger models especially ) often includes a lever to push sides of the handles apart to unlock the pliers.
 

Locking pliers are available in many different configurations, such as needle-nose locking pliers, locking wrenches, locking clamps and various shapes to fix metal parts for welding. They also come in many sizes.