Use the Down River Oar Tower Bases to attach the Down River Oar Towers to your frame. 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 XD (1.5" nominal) or DRE LD / NRS (1.25" nominal) frames. Towers are 1.5" nominal only and will fit in either the LD or XD Base.