This pillow can be used in conjunction with any mask during sleep. Mask types include; sleep apnea, CPAP, BIPAP, NIPPY & more. Pillow has specialized cut-out's to reduce pressure on the mask when side sleeping. Pillow is also designed to correctly support the body and reduce neck, shoulder & back pain. CPAP Pillow features: Cut-out's to reduce pressure on mask when side sleeping Fitted, removable & washable cover Ergonomic design to support head, neck & shoulders Pillow design reduces "blow out" into eyes for air leakage Wake up with less "angry red lines" on face Handmade in the UK with a 2 year guarantee Helps heal & comfort: Mask discomfort & non compliance Better fit during the night Side sleeping with a mask Neck, shoulder & back pain Headaches & numb arms Size: Small for petite adults or children - 52 x 31 x 9.5cm (23 x 13 x 6") Medium for most female frames and smaller male frames - 52 x 31 x 13cm (20.5 x 12 x 5") Large for larger female frames and normal male frames - 58 x 33.5 x 15cm (23 x 13 x 6") All sizes fit into a standard pillowcase. Mask sold separately.