Andersen Window - Operator Channel / Track 14-1/2 inch for 7073A 7073B - New Style Andersen 14-1/2 inch Channel is made for 7073A 7073B Operators with square plastic swivel buttons on the end of the Operator Arm. They were used by Anderson from 1960-1974 . Channel will work with both Left and Right Hand Operators. This track will work for both left and right hand Operators Also works on Operators with round or square buttons. The New Track style has a grove on both sides and a notch in the center. The Old Track had a groove on one side and no notch. Note: Normal signs of use.