Truth 50.70 Maxim Reverse Dyad Arm Operators are designed for narrow casement windows from 12" to 24" up to 72" high with a maximum sash weight of 53 lbs.
The Reverse Dyad Operator is also used for specialty windows (i.e., round tops, half round, trapezoid, garden, octagon, and windows that use butt hinges or 4-Bar Hinges)

Truth Maxim Dyad casement operator for Sill mount applications, wood or vinyl windows
Markings: Truth link number: 31876
Used by SNE, Crestline, Hurd, Bilt Best, Weathershield and others

Glass Size: 12 or 24 inch casement window
Arm Link: Offset Up - Then Down
Link Length: 5-3/8 inch
Link Hole Centers: 5 inch
Link Height: 39/64 inch (15.4 mm) .606
Clip: None, Snaps on
Color/Finish: Limited to colors shown
Handed: Yes, as shown

Additional Information:
Truth Dyad Arm Maxim Casement Window Operator has a die cast body with stamped steel arm. This new sleek style window operator uses a contoured handle and sealing gasket, both of which are sold separately. It is used by several window manufacturers. Crank handle sold separately. The recommended screws are 6 pieces of #8 x 1 Flat Head, Sheet Metal Screws.