Ideal for aluminum single-barrel and copper double-barrel sleeves, the professional-grade Pro Crimper is heat-treated and chrome-plated for increased strength and corrosion resistance. Spring loaded with articulated jaws and a cushioned handle for easy crimping. Use with crimps with a .1mm to 2.2mm outside diameter. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Crimpers.