As the shock absorber opens up, it allows another 3 and a half feet to play out. The body harness will stretch about a half foot. Add in the distance from the D ring to the worker's feet, which is generally about four feet. Adding all this up and you fall 14 feet, hitting the ground at twelve feet. There's more to it than just thinking a six foot lanyard will stop you at six feet.
Many lanyards are only three feet because of the stopping distance required.
Now, let's review the lanyard. The lanyard is attached to the body harness between your shoulder blades and to an anchoring point. There are different kinds of lanyards, such as nylon webbing, rope and shock absorbing. The nylon webbing is strong, but it has no flexibility, in that it doesn't give when stretched. This means your body absorbs the full force of the fall.