Gedore 5mm Nut Driver - For Internal Nipples From  £17.98

I bought this for truing my Neutron wheels, which it does. So very pleased with it :)

Bought this to fit on the spoke nipples of my Campag Neutron Wheels for truing. Its small enough to fit through the hole and fits properly on the nipples. So this product does the job nicely.

The only problem I had was that the spoke twisted when I twisted the nipple, so you have to find a way of holding the spoke to tighten or loosen it. Personally I used the flat area of a pair of long-nosed pliers which did the job nicely. I find the wheels, which are relatively new, need truing fairly regularly. I guess they will eventually settle down after a while, until the next pot-hole.