A standard drawer runner style, side-mounted runners affix to either side of the drawer, leaving them visible whenever the drawer is open. Most of the less expensive drawer runners are side mounted, such as Blum's "Standard" and "Metabox" designs. Side-mounted drawer runners generally affix to wooden drawers, a common material for cabinetry, though you can also find them with hardware for attaching to metal or plastic drawers.
A more aesthetically-minded alternative to standard side-mounted runners, bottom-mounted drawer runners are invisible throughout drawer operation. Some manufacturers may also refer to them as "under-mount" or "concealed" runners. If you're planning to install the drawers yourself, first check whether installing side- or bottom-mounted runners is easier, paying particular attention to the orientation and workspace around very low drawers.
Whether you opt for side- or bottom-mounted drawer runners, heavy-duty runners will best complement very large or heavily-laden drawers. They serve particularly well for commercial or industrial uses, as in workshops or professional kitchens. To appropriately select drawer runners for a new cabinetry system, first estimate where you will store various items. For example, if you foresee that a specific drawer in the kitchen will contain heavy cleavers, mallets and knives, you may wish to install heavy-duty runners on this drawer. Accuride's "Heavy-duty" slide accommodates loads of 75 to 200 lbs.
Soft-close drawer runners may be side- or bottom-mounted to fit your budget and tastes. As the name suggests, they avoid slamming or noisy closes by guiding the cabinet to a "soft" meeting with the cabinet frame. Futaba's "Soft-close" designs use ball bearings and bear loads of up to 100 lbs. They require that the height of the drawer is at least 1/2 inch less than the total height of the cabinet opening, even if side mounted.
Self-close drawer runners are a premium style, generally offered as under-mount runners. A gentle push on the drawer causes it to continue closing until it softly shuts. The convenience of a self-close drawer may aid in the fast-paced environment of a commercial kitchen or add elegance to a residential application.