Ideally the lasers should be 2cm away from the scalp for optimal therapy. If the cap is resting loosely on your head that is perfectly okay. The fit does not have to be tight but the closer the lasers are to your scalp, the better. If there is a bit of space on the sides of your head that is alright as well.
Our regular size caps fit most, with a head circumference of up to 24". If your head circumference is greater than 24" inches, please contact the Capillus customer care team to request a larger size.