The Eson Nasal CPAP Mask and Headgear was created with easy fit and comfort in mind. Adaptive Fit The slim frame of the Eson utilizes RollFit technology which comfortably adapts to movement and reduces pressure by rolling at the bridge of the nose. A ball and socket elbow complements the masks lightweight design offering a wide range of movement and a reduction in mask drag. While all Eson mask frames are the same size, cushions are available in small, medium and large. The forehead bar of the Eson adds additional adapation for the cushion by anchoring the cushion while allowing for movement. The forehead bar holds enough support to help keep the seal from moving too far, but allows enough movement to help maintain a seal during position changes in the night.