What it is

The sticks and chains are the tools used to measure whether the offense earned a first down. Two poles are linked by a ten-yard chain.

In a game

A crew holds them at the sideline. One pole marks the start of the series and the other marks the line to gain.

More detail

They are used for close measurements, when the ball is near the line to gain. A down marker also shows the current down. The system is old, and the chains are still brought out for the most disputed spots.