Easy to put on: The kit's size-adjustable mask allows for quick and easy acceleration, adjustment and retraction to fit all head shapes. Comfortable to wear: The mask is made of rubber and offers a comfortable feeling for the facial skin. Soft rubber does not cause discomfort and is ideal for long work sessions. Ingenious design: The cold flow breathing valve design reduces breathing resistance. The mask is equipped with an easy-to-adjust headband for most head types