Note: multiple size and length options may be available. Cost will vary. Search Amazon for “Reflectix”
Possible homebrew application: Use to insulate to your compatible keg, mash tun or HLT to help maintain temperatures. Cooler hack… I use this for my coolers (regular ole cooler as a cooler, not mash tun). I cut a piece to fit the top of each cooler (fitting it to the cooler size as tightly as possible) and place on top of food or ice to provide an additional layer of insulation.
Reflectix Insulation, 24 in. x 10 ft. – note that multiple variations of this product may be available, as such a different version may appear at this link
Make sure the components you use are compatible and rated for your intended application. Contact manufacturer with questions about suitability or a specific application. Always read and follow manufacturer directions.