Looking to upgrade your HD4 gantry to the linear rail system of the HD5? The HD5 gantry system will bolt directly to the HD4 base giving you the increased performance of lineal rail guides, aluminum router mount, steel encased legs, and a cleaner look with Z motor wires running through a channel in the leg. Wondering what to do with your current Gantry? "That's easy trade it in." NWA will allow a $500 credit upon receipt of your used HD4 gantry when upgrading to the HD5 gantry. Simply use the HD5 gantry shipping box and included paperwork to ship it back to NWA and receive a $500 refund.