This header drive chain transmits power from the gearbox output to the rotating cutterbar and auger assembly. It is a roller chain that engages sprockets on both the drive and driven shafts. A worn chain will slip under load, causing intermittent header speed and uneven crop feeding. The half link included in the set allows the installer to achieve the correct tension without an additional master link. On installation, verify the chain runs in the same plane as both sprockets and adjust the tensioner to the manufacturer's specification.