Spectre's Air Duct Hose is designed to attach directly to an air box inlet, plenum, intake tube or mounting plate with a 4 inch outside diameter to bring cooler air into the engine. Multiple pieces can be threaded together for longer applications, and with a memory-flex design to help retain position, this easy bending hose is versatile and easy to setup. This kit includes 41 inches of ducting and 2 threaded PVC couplers.