Sometimes you need to tighten a bolt or make a few adjustments on your bike. What you need, then, is a lightweight multi tool from Crank Brothers. For most folks the m5 will sort you out. It comes with 3mm, 4mm, 5mm, & 6mm hex wrenches and a phillips head screwdriver. For bikes with disc brakes and rotors, there's the m10. It comes with everything the m5 has plus 2mm, 2.5mm, & 8mm hex wrenches, flat screwdriver, and t-25 torx wrench. Available at the shop, $13 and $20.