Negative Positive
Title: Don't move, vibrate, tilt or press too hard...
Review: I use these at my automotive school, notorious for un-calibrated torque wrenches and people who don't like reading directions. I would go with professional grade set if your working on rusted bolts, or in awkward or tight situations. Otherwise, for light to medium duty work: Buy 2 of these sets to save on shipping. You will need the extra set. The slightest vibration can snap the bits, they are very brittle. Consider your first set a 'learning set'. If you use them to remove another bit that has broken off in a broken screw, they grind into dust (Doh!). These work great on bolts which have been over torqued or snapped on re-install.
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