The Down River Oar Tower has a 12 degree angle cast in the head to allow the shaft a perpendicular position in the oar lock without having to tilt the tower out itself. Oar towers and bases sold separately and individually. If you need a full pair, you will need to order 2 appropriately sized bases, and 2 towers. Bases sold for either DRE (1.5" nominal) or NRS (1.25" nominal) frames. Towers are 1.5" nominal only and will fit in either the NRS or DRE Base.