The new Pro 3 Plus bicycle rack is technically an upgraded Pro 3 bike rack with an Universal Fork Mount Base, able to move between different fork mount sizes when you have 2 or more bicycles. The Universal Fork Mount Base requires an additional interchangeable plug set (sold separately on the Accessories page). This system allows customers to change front axle sizes Plug Sets quickly, to support and transport different bikes, without changing fork mounts. After you select a Pro 3 Plus rack, please go to the Accessories page, to add those Plug Sets you would need to carry your bicycles. To understand the differences between the Pro 2 versus Pro 2 Plus, please check out the description of the Pro 3 Bike Rack (if you need any help, please contact us through email or LiveChat).