Rugby Union/Lock

There are 2 locks on the field at one time. They are in the second row of the scrum. They also get lifted in lineouts.

In the Scrum

 * Keep the front row stable by backing up the props
 * Guide the ball to the 8-man with their feet
 * Provide a handhold for the flankers

In General Play

 * Follow the ball, providing support for the runner
 * Be active in the ruck
 * Be ready to run the ball into the other team's defense
 * Be ready to tackle the other team's big players

In the Lineout

 * Responsible for getting the ball from the throw-in
 * Try to take the other team's throw-in
 * Is lifted into the air by props