While the original Blue Oasis provides sufficient humidity in many environments, it is not effective everywhere. The humidity demands of the desert, mountain states or frigid north exceed the humidification capacity of the OH-1. For this reason, we have developed the OH-5 Plus+ humidifier. The OH-5 Plus+ is the same size and shape as the original blue Oasis, but is has a different liner which provides 50% more humidity output. Because the OH-5 Plus+ is the same size as the original Blue Oasis and it has 50% greater humidity output, it will be necessary to refill the Oasis OH-5 Plus+ more frequently than the original Blue Oasis. Use the OH-5 when the environment outside the case has a relative humidity of 25% or less.