Kraft Plastic Concrete Sliders/ Knee Boards 30" x 10" (Pair)This pair of 30 In. x 10 In. concrete sliders skids is made from tough, heavy duty polystyrene plastic. The knee boards has rounded edges to prevent digging into concrete. The polystyrene resists corrosion from use and makes the boards easy to use and the plastic makes them easy to clean. The white material can be used with white and colored concrete with confidence. Toe bracket secures the foot and allows for an ease of back and forth movement along