There are three common types of leaf blowers on the market: corded electric; cordless electric (battery powered); and gas. Most are handheld, although heavier models are backpack mounted. Wheeled, walk-behind models are better suited for stadium-sized lawns and professional landscapers. Some models, referred to as 3-in-1 blowers, incor­porate a vacuum function that shreds leaves and deposits them into an attached bag. Corded models are the lightest, quietest and least expensive. Cordless blowers are gener­ally heavier and noisier. Some of the newer models can deliver as much power as gas blowers and up to 200 minutes of run time per battery charge on the lowest power setting. Gas models, which typically use two-stroke engines, are the heaviest and loudest, require the most maintenance and are highly polluting. An increasing number of munici­palities are either limiting the hours of use for gas blowers or banning them entirely because of noise complaints. A leaf blow­er’s electric motor or gas engine powers an impeller (a fan blade) at high speed to gener­ate centrifugal force that draws air into the blower housing and out the blower tube. Blower power is rated by CFM (how much air the blower puts out). How fast the air moves (measured in MPH) is less important. Some models have variable speed and a turbo boost mode to dislodge clumps of wet leaves.