These industrial-grade steel wrenches work in tight spots when ordinary allen keys won't. Each has one ball-end, permitting entry angles up to 25 degrees (the other end is standard).

This metric-fit set of 7 wrenches includes the following sizes:

1.5mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm

I use them in the workshop all the time – just the job on Far Eastern and European parts.