This helmet is the same as the BT PX210 with more silence! Most: comfort: small - foldable - comfortable - does not serve the ears and not too néchauffe sound: perfect! the silence obtained by the noise reduction system is very pleasant in transport - does not abuse go on serious and very acute - in terms of quality no negative feelings when we are bluetooth. Autonomy: nothing to say, very fast charging by USB and ample autonomy
In short I recommend to all. The model MM 550 x is the same with just the earbuds that encompasses more and therefore certainly improves tuned, but I doubt it.
