CB Series hinges are concealed bearing hinges that have vertical and lateral wear performance that exceeds ANSI/BHMA Grade 1 standards. Best patented a revolutionary bear construction called LifeSpan to eliminate metal-to-metal contact between knuckles. As the stainless steel washer extends into the sleeve, it eliminates metal-to-metal contact between the pin and barrel, resulting in a smooth, quiet operation superior to that of a ball bearing assembly. In addition, the concealed bearings allow for fewer horizontal barrel lines that provide a more seamless appearance. The CB Series is ideal for medium to heavy weight wood and metal doors in high frequency usage applications. All hinges have template screw hole location for use on either wood or hollow metal doors and frames. Approved for use on all types of fire doors up to 4' x 10' (1219mm x 3048mm); 8' x 10' (2438mm x 3048mm) pairs, to maintain the integrity of fire rated openings and walls; refer to NFPA80.