The Truth Hardware (AmesburyTruth) 15 Series Ellipse Left-Hand 9-1/2" Single Arm Casement Window Operator (15.31) is designed for seamless operation in casement windows, pairing perfectly with AmesburyTruth 14 Series Casement Window Hinges. Often referred to as a window crank, window mechanism, or window opener, this left-handed operator is engineered to support window sashes up to 48 lbs (22 kg), with widths ranging from 20" to 24" (508 mm - 610 mm) and heights up to 65" (1651 mm).

This operator is commonly identified with the stamp "40049" on the arm, though you may also find the stamp "45135" on the base of the operator.