Emissions regulations have eliminated noisy and polluting two-stroke engines from most applications, but these engines still dominate in lawn equipment like string trimmers (aka weed eaters, weed whackers, line trimmers, weed whips) and leaf blowers. Lehr, a startup based in Los Angeles, has developed a cleaner and quieter alternative–small engines that run on 16 ounce propane canisters used for camp stoves.
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