The PX100 II does not live up to its predecessor. The protective case is actually a cover (which does not protect shocks) while the first was supplied with an ingenious housing. The audio quality is identical to the first generation PX100 but I heard my helmet saturate some serious which had never happened to me before. But it remains generally in a Sennheiser product and quality is there. My disappointment comes mostly from the first generation to the second passage.