The Black Hawk Abrasives 4.5” x 7/8” T29 Flap Disc for Aluminum is a breakthrough in soft metal grinding technology. With premium ceramic grains, calcium stearate coating, and sturdy polyester flaps this 4 ½ inch sanding disc will stay cool, prevent loading, and last very long. The secret to this disc's effectiveness and longevity is in the white stearate coating. As the disc is used the stearate becomes liquefied, creating a protective barrier on the work piece, both lowering the work piece's temperature and preventing clogging (A.K.A. “chip adhesion”) on the disc itself. Under the same conditions a standard zirconia or aluminum oxide flap disc may distort or warp the work piece while gumming up, drastically reducing the useful life of the flap disc. For these reasons the BHA's Aluminum 4.5 inch flap disc is the ideal choice for all soft non-ferrous metal sanding applications including copper, nickel, zinc and of course Aluminum! To maximize your effectiveness, reduce disc change down time, and protect your material look not further, this is your flapper disc.