This pillow is designed to be used by mask wearers during side sleep. The two "C" shaped cut out's on either side take pressure off the face leading to deeper & healthier sleep. Mask types include; sleep apnea, CPAP, BIPAP, NIPPY & more. Product features: Cut-out's to reduce pressure on mask when side sleeping Medium-soft density (molded foam) Fitted, removable & washable 100% cotton 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 3 3/4") Medium for most female frames & smaller male frames - 52 x 31 x 13cm (20.5 x 12 x 5") Large for larger female frames & normal male frames - 58 x 33.5 x 15cm (23 x 13 x 6") All sizes fit into a standard pillowcase. Mask sold separately. Spare CPAP pillow covers available here. Also available in memory foam (Very firm).