Reclaims heat from your stovepipe and radiates the heat into your room Made of 28 ga High Thermal Conductive Alumiinum. Draw more usable heat from your stovepipe. Fits 11.5 inch circumference (3.6 inch diameter) double wall insulated stovepipe used on pellet and corn stoves. Made from 28 ga. aluminum 1 1/2" wide Heat / Fuel Saver. They pay for themselves in a short period of time. Install in 10 minutes they snap on and will last a lifetime. They never need maintenance. 3.6 inch dia (11.5" cir) stovepipe heat exchangers (set of 6 snap-on bands)stovepipe reclaimer / radiator rings that extract heat from the hot stove pipe and radiate the heat into the room. Will fit a double wall insulated stovepipe, 11.5 inch circumference, typically used with pellet and corn stoves. They make close contact with your stove pipe and extract more usable heat from the hot pipe.. Just like the aluminum fins on a motorcycle engine, they increase the surface area of hot, exposed metal and allow more heat to be radiated and released. Made of 28 gauge high thermal conductivity aluminum. Attach quickly and easily to your stovepipe, no screws or tools are needed. The ends lock into each other, taking about10 minutes to attach all six radiators. The bands conduct heat from the points of contact on the stovepipe to the loops in the band where the heat is released into the room. See my other listing for 3, 4,5,6,7,and 8 inch diameter. They will last a lifetime and may be re-used if you replace the stovepipe. They never need maintenance. Put on as many bands as you wish. This set of six will cover a 9 inch length of pipe. . NOTE: The length of stovepipe in the picture is not part of the sale.