There are 3 sizes: 
 - Very premature: <28 weeks
 - Premature: 29-36 Weeks
 - Premature/Newborn: 37 Weeks 
  
 The Bilibonnets are   studied for premature and very premature babies.
 The shape of the  glasses allow total blocking of light, adapts to even the smallest premature babies.  The mask has a soft and non-slip material, this allows protect the eyes of premature babies in the phototherapy device. With a stretchy mesh cap that ensures a secure fit without any pressure on the eyeball of the child who may blink, thus lowering the stress level.