Park Tool AWS-9 Fold Up Hex Wrench Set
The AWS-9 Hex Wrench set combines all the most popular hex wrench sizes along with Phillips and flat blade screwdrivers into one convenient fold-up tool, eliminating a mess of individual tools. The multi-position composite handle is comfortable, lightweight, slip-resistant and 40% stronger than steel handles.
This is the best light weight tool IMHO - sure you can carry the kitchen sink in your pack, but is it worth the weight? On most day rides I say no.