Hercules rebar chairs and footer stands are made of polypropylene copolymers. Available in two sizes, the chairs meet the requirements of a CRSI Class I bar support. The 911 features 1.5-inch clearance and fits #4 rebar; the 912 has 3-inch clearance for #5 rebar. The 924 footer stand also fits #5 rebar. T. J. Harris Co. 865-633-9955. www.herculeschair.com .