Deck WidthThe deck diameter of your lawn mower dictates how wide a swath it cuts as it passes over the grass. Bag: The vast majority of mowers come with a grass bag to collect grass clippings. Self-propelled lawn mowers are a little more complicated, but make your life easier. Most mowers come equipped with one, two, or four levers to adjust deck height. The only thing you need to check and replace is your lawn mower blade (you can also learn to sharpen it yourself).