The Grip-Rite ProLok high chairs and tilt-up chairs have a locking head that raises rebar or reinforcing wire mesh to the proper position and secures rebar intersections with no tie wire or bar ties. Eliminates 50% of the tie wires in a mat and is stackable for multilayer grids of rebar. The tilt-up chair has a four point base and nail holes to attach to forms. PrimeSource Building Products. 800-727-7338.