http://www.thitco.com/building....-material/concrete-s Sturcture Accessories factory Category of Rebar Spacers Plastic Circular Spacer Plastic Circular Spacers (also known as Circulars, Wagon Wheels, Fastwheel Spacers or Wheels) is the most extensively used circular spacer for precast and on site concrete applications. Plastic Circular Spacers feature large clamping range for different diameters. They provide 360 degree coverage where reinforcing mesh or bar is placed in a vertical position as in walls or columns. Concrete Cover: 15mm-75mm Bar Size: 4mm-26mm Plastic Top Deck Rebar Chair Spacer Plastic Top De