These awning arms are 10 feet (3 meters) long each.
This product is a set of two arms: one right, and one left.
For awnings that are 12 x 10 feet, you will need two arms total: (1) right arm + (1) left arm.
For awnings that are 13 x 10 feet, you will need two arms total: (1) right arm + (1) left arm.
For awnings that are 16 x 10 feet, you will need three arms total: (2) left arms + (1) right arm.
For awnings that are 20 x 10 feet, you will need three arms total: (2) right arms + (1) left arm.