The Knee Nailer was designed to reduce the grind of hand nailing. It is constructed of highly durable polyethylene with wide, stable wheels and a removable, 1″ heavy-density foam pad to kneel on. The top of the unit is 3-3/8” off the ground. By placing one knee on the cushioned surface, an individual can roll comfortably along the length of the line without having to constantly get up and down. With 2000 nails in one court, this little accessory provides big relief.