This is a 12" straight extension cord for an existing sync cord. Sync cords provides the necessary connection between a power pack or monolight, and a camera, or triggering device that has a female PC (post connection) terminal.
Straight cords are lighter, and usually more economical than coiled cords; coiled cords stretch when necessary, and are more heavy duty than straight cords.
Premium sync cords have gold-plated ends, for longer lasting sure connections.
So, I modified an older RRS L plate using a friend's milling machine to fit my 5D3, but that meant the aperture didn't line up completely with all the connectors on the side of the 5D. So, I purchased this to install underneath the L plate as a permanent tail. The male PC to female PC allows me, in effect, to move the connector off the camera and attach a flash sync cable at any time, without having to remove the L plate. The short length makes the dangling end pretty much unnoticeable. Cable seems fairly well constructed, and well worth the price!
Cable is sturdily constructed. Make sure the cable ends are the right type: male-male, male-female, female-female. The ends are small and the male and female ends look similar.