Set of six, 3 inch diameter aluminum stovepipe heat extractor / reclaimer / radiator rings that extract heat from the hot stove pipe and radiate the heat into the room. They will fit 3 inch single wall, non insulated stovepipe. They make close contact with your stack / pipe to draw more heat out of the pipe. Like the aluminum fins on a motorcycle engine, they increase the area of heat dissipation. Heat is conducted into the radiator loops where the heat is transferred into the air. They are widely used as stovepipe heat exchangers that reclaim heat from the hot stove pipe and radiate the heat into the room. They are made of 28 gauge aluminum, 1 ½ inches wide. They attach quickly and easily to your pipe or exhaust stack. No screws or tools needed. The ends lock into each other. It takes about 5 minutes to attach all six radiators. The bands conduct heat from the points of contact on the pipe to the loops in the band where the heat is released. They will last a lifetime. They never need maintenance. They are guaranteed to draw more heat from the pipe. You may put on as many bands as you have room for. One set of six bands covers 9 linear inches of exposed pipe. ***PLEASE*** measure your circumference with a flexible tape or string. (Circumference divided by 3.14 = diameter.) See other listings for more sizes. (3, 3.6, 4, 5, 6, 7, and 8 inches) NOTE: The length of pipe in the picture is not part of the sale.