RTU can be immediately installed after curb installation. Roofing membrane/flashing can be finished later, at the customers convenience, without removing the unit reducing the cost of installation and expediting installation. Spring isolators are sized/located for minimum 90% isolation efficiency with 2” deflection and are adjustable for unit leveling through removable access panels. Weather resistant bulb seal is preinstalled at the factory. The curb is constructed of prime G90 galvanized steel meeting ASTM requirements. All exterior seams are fully welded for a watertight seal. Internal full height dividers provide curb reinforcement. Curb can be pitched to match roof slope to level top of curb.