This multi-tool from M-Wave is not only incredibly useful but will fit in the palm of a hand. Throw it in a pocket or bag to carry with you for adjustments on the fly.
15 functions in a convenient package
Includes 2/2.5/3/4/5/6/8 mm hex bits
Also includes 2 Phillips and 1 flat screwdriver heads
Also includes T25 Torx and 3.2/3.3/3.5 Mavic spoke adjusters
Also includes a chain riveting tool