This extreme duty replacement set of two snow blower shoes is designed to lift snow blowers up over sidewalk cracks up to almost 2 in. Bottom runners are 12 in. long, and are CNC cut from 1/4 in. thick steel plate, more than twice as thick as many stock skids. You may have bent your stock ones, but you are not going to bend these skids. By design, 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. Armor skids provide a ski-like glide over uneven terrain, exactly what is needed for gravel driveways. This skid size has five slots: two slots on 2 in. centers, two slots on 4.75 in. centers, and a center slot. Slots are designed to have a slightly loose fit on a 3/8 bolt. Washers required (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. Patent 8544856.