The TorsionX MaxDrive .7 is the smallest square drive tool available. Small but very capable and perfect for those smaller bolts on hard to reach places. With all the great features of the bigger MaxDrive tools like steel reaction pawl levers, fixed shroud and rough teethed ratchet. Especially great with the optional Multi Directional Swivel providing even more flexibility.
Below is an example of a small toolkit which includes a Lokrite Safety Backup Wrench.