Clamp On Heat Shield 4″ x 1 ft. This flexible clamp on heat shield blocks more than 90% of damaging radiant heat from the exhasut system. Teh high tech composite construction provides the ultimate in protection incorporating T-C-T Thermo Tec`s proprietary coating technology. Clamp on shields are available in 1ft 2ft and 3ft lengths complete with clamps. 4in or 6in diameters only.