This unique Truth Hardware Dyad Casement Operator provides smooth, continuous control of casement and single vent awning windows. The dyad, or two-linked design, provides smooth operation of windows. The detachable clip linkage allows this window operator to be disengaged from the sash for easy assembly and installation. Machine screws, set five inches (127 millimeters) on center, thread through the window frame and into the back of the operator case for mounting. Crank handle is not included. Common numbers that can be found on these Truth Hardware Dyad Casement Window Operator are 30866, 30614, 30593, 30615 and 30894.