The Dorma 8832 Top Arm with Channel for RTS88 is for use on Double and Single Acting Doors. We usually find this arm on wood doors. This arm is 10-5/8" long by 1-1/2" wide at the widest point, and is 5/8" thick. It is the standard arm in the RST04, RST05 and RST06 packages.
Dorma Part # 8832