Kelly bars and extension shafts for digger derrick augers. This is the bar that goes down inside the tube of the auger and connects to the drill motor. If you need to get deeper in the ground or just need a new bar these are what you want. There are two styles one is just a hex bar. The other is a hex bar with the hex female hub on one end this one being the extension. These can be used to change bar size if you purchased another drill and the bar size is different then all your current augers.