Premium Mask Sizing LiveO2 supports 4 different sizes of mask. Sizing Steps: Download this sizing guidePrint on PaperHold the paper to your faceReport the size required. Updated on August 11, 2020 Was this article helpful? Yes No Related Articles How fast can I ramp my exercise? Mask Kit Introduction How to clean masks Use a neoprene headgear with a premium mask System Setup Check How to Setup a System for the First Time