In extremely dry environments, like the desert Southwest and mountain or frigid North, where the relative humidity stays below 25%, guitars need increased humidity protection. The Oasis Plus+ humidifier is designed to produce 50% more daily humidity than the original blue Oasis to supply this additional humidification. Since the Oasis Plus+ is the same size as the regular blue Oasis, it will need to be refilled more frequently. A refill syringe is included with every Oasis humidifier. • MFSKU OH-5 • UPC 898775001038