RGS - 6ft Threaded Rod UpgradeAdd this product to an existing 48 inch capacity threaded rod unit to upgrade the unit to a 72 inch width capacity You will also need to add a 27 1 2 Inch Rail Extension Kit to your order in order to have the correct length extrusions to utilize this threaded rod. For example, you want a 6ft x 8ft capacity system, but would like to have the 6ft bridge with a threaded rod for indexing Start with a 48x96 threaded unit, add one 27 1 2 inch extension kit,