Think you know everything there is to know about power tools? Today you'll learn about power-tool trigger locks. Many of today's power tools come with a trigger lock, a handy little device that allows the tool to run without having to hold down the trigger. Just push in the little hold button. That's all you need to know, right? Wrong. That's how you can get yourself in trouble. If, say, the power goes off because the plug pulled out and you lay the tool down to reinsert it, the next thing you know is the power is back on and your power tool is back on as well -- with no one at the controls. To prevent possible project damage and potential injuries from runaway tools, make certain they're turned off before you lay them down to check out a problem. The same goes for toggle-type "on" and "off" switches.