Screws are great until you go into the local coffee joint and tear up their hardwood floor, or walk on concrete and skid, breaking your hip. My favorites were carbide cleats made by Get-A-Grip. Easy on, easy off, less than $30 a pair, and last for years. Frabill has a similar set up, retailing around $10, if you can find them in stock. Perfect for the wind blown, slick ice I always seem to be on.