The secret to keeping NFL games on track is this little chain clip

With 2:10 left in the Dallas Cowboys’ game against the Green Bay Packers in Week 5, Ezekiel Elliott was stopped on a key fourth down and the ball was awarded to the Packers. The chains moved and everyone got set up for a Packers’ first down.

Except Cowboys coach Jason Garrett threw a red challenge flag, the replay showed a different spot for the ball, and suddenly the referees needed to measure for a first down.

Damn it! The chains had already moved. What could they do now to get an accurate measurement?

Enter ... THE CLIP!

The clip is a little contraption designed as a fail-safe for the chains. It is placed every time the chains move after a new first down is gained to mark a spot where the chains can reset if necessary.

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There are two main reasons the chains could move when they’re not supposed to: 1) a runner is barreling down on the person holding one of the stakes and they need to move out of the way or get crushed; or 2) as in the above example with the Cowboys, the chain crew moves the chains intentionally but at the wrong time.

In these instances, the chain crew just puts the clip back on the yard line where it was, pulls the chains tight and BAM! It’s like they never moved.

The clip also comes in handy for a movement of the chains after the first quarter, when teams swap sides of the field. Instead of trying to “eye” the chains into the right spot, someone picks up the clip — let’s say it’s on the 35-yard-line — and the chains move, putting the clip on the new 35, stretching the chains. Again, they’re ready for the next play.

The clips come in one of two styles. The plastic clips are circular and rotate to show the yard-line it’s on, just in case someone forgot where it had been set. The cloth clips are strips with a small plastic “window” to identify the pertinent yard line. In both the NFL and college football, both styles are used, generally depending on the preference of the down judge, head linesman, or team.

In a game of inches, it’s actually critical which side of the yard line the clip is placed on the chain. “Which SIDE of a yard line?” You might ask. “What does that mean?”

Yard lines are all four inches thick (that’s even in the rulebook or game manual). If the DJ/HL is not precise about where on the yard line the clip is placed, and where it needs to be during the official measurement, she can get an incorrect measurement and incorrectly cost (or grant) a team a first down.

For consistency, the clip is universally placed on the backside of the yard line, which means the side of the yard line closest to the goal line from which the offense is moving away.

On a measurement, the DJ/HL takes the clip and walks the chains onto the field, placing the clip on the back end of the same yard line. When the chain crew pulls the chains tight, VOILA! They have exactly replicated where the chains were on the sideline for a perfect measurement.

On a chain crew, it is one person’s role the entire game to simply manage the clip. Yes, that makes it as important as the box or the chain itself.

At the most crucial time of a Packers-Cowboys game, having that clip in the right spot can be the most important element of the game’s management.

Cyd Zeigler is a high school and college football official in Los Angeles. He is also the co-editor of SBNation's Outsports.com.