Every suburbanite worth his sod knows: There’s more to an enviable lawn than a crop of dense, dark green blades. The details matter. The best-looking lawns are not only well nurtured but also well groomed: free of weeds and tall, mangy spears of grass, bordered by a crisp, defined edge. String trimmers can cut a 10- to 15-inch-wide swath and are the fastest way to get into areas a mower can’t reach – against the house or a fence, or between shrubs. They can also pull double duty as an edger to carve a defined border against walkways. Luckily, better builds and stronger motors have eliminated some of the headaches the machines used to cause. Here are three of the best.