The Dorma 8835 Top Arm for RTS88 is for use on Double or Single Acting doors that have a 1" top rail. This arm is used on aluminum framed glass storefront doors. The arm is 10-7/8" long and 1-3/8" wide. The spindle lug 1" thick. This is the standard arm on the RST07 and RST10 packages.
Dorma Part # 8835