Armorskids PRO Series is designed exclusively for the Snow Removal Professionals who run their machines nonstop, the new professional series has a full 1/2 in. T steel bottom runner for long life. Extreme duty replacement snow blower shoes set is designed to lift snow blowers up over sidewalk cracks up to almost 2 in. Bottom runners are 12 in. L, and are CNC cut from 1/2 in. T steel plate. The leading edge of our skid is moved forward, to protect and gently lift snow blowers up over bumps. The angle of the leading edge is less than half that of most stock skids. For every bump the skid encounters, it has more than twice the distance to lift the snow blower up, compared to a stock skid shoe. Made with American Steel. Gravel is brutal on snow blowers. Stock skids dig into gravel, leave ruts, and bend when they encounter frozen rocks. Armors kids provide a ski-like glide over uneven terrain, exactly what is needed for gravel driveways. Details: 2 slots spaced 2 3/4 in. apart, plus 4 additional slots that allow skid to be mounted slightly forward if needed. 6 slots total. Slots are designed to have a slightly loose fit on a 5/16 in. bolt. New bolts and washers not included. Note that due to size of skid there may be clearance issues with other bolts or protrusions on the snow blower. Either use the old skid as a spacer, or large fender washers to space skid further outward if needed. Patented. This item is a matching set of 2 skids.