The Headphone range is made for different size heads and like most headphones each will be better suited to different head shapes and sizes. The MK01 being the smallest will be better suited to Small to Medium size heads, and the MK03 has a larger range being suitable for small all the way to large size heads. To check the size will fit you we have a method for checking: if you were to measure from the center of one ear to the other over the top of your head with a tape measure or piece for string this will give the you cord length. The cord length for our headphones is as follows:
MK01 34 to 40 cm.
MK02 36 to 41 cm.
MK03 37 to 42 cm.
Please see the size guide HERE: