What is this bike tool? I've bought a saddle bag with a set of bike tools; stuff like alan keys, puncture repair kits,  spanners etc. There's this one tool (well two but they screw together) that I have trouble recognising. 

I know for sure it's not part of the installation of the saddle bag. It also didn't come with any instructions.
Its a Chain tool, the long bit should screw into the back (bottom side in the pic) of the other bit to provide a handle. You can then put an hex key into the twisty bit at the right hand end.