Pre-Order your Commemorative Ball Marker for USC’s 11 Football National Championships today. The two-sided larger “Duo” Ball Marker is 42 mm in diameter and holds a removable standard size (24.5 mm diameter) two-sided ball marker in the center of the front side with a strong magnet. The smaller, standard size marker is removable to give the player two options on how to mark his/her ball on the green. This Duo Ball Marker is much more than a golf ball marker, it is a commemorative coin that will be found in trophy cases, on office desks and USC fans pockets around the world. The Commemorative Duo Ball Marker is packaged in a fashionable tin box to make it a perfect gift item.