The helmet fits our small very well. We have taken him in the same M and currently he wears it on the smallest stage and loves him very much! The initial setting of the helmet belts is something complicated. If you, however, ever set a helmet adults (and indeed all parents have already made at least in their own helmet) it is not very difficult. It just takes a few tries before you hit the right length, the child should therefore be in a good mood. If the helmet is bought slightly larger as ours remains much Helmet band left (about 20cm) and then hangs. Our child does not mind. You could call it the fold with supplied clasp however high or stuck or cut (but not too much else is cut later in the Greater provide too little band there.) The helmet is very light which was one of the main criteria for us. The fit is very good and flexible with soft fabric strips gepolsterst so nothing can press. He also goes behind the ears and neck deep down like an adult helmet so that even then protection is given when the helmet it out a bit should slip.