I purchased this hat with the new 455 Balanced Regulator. Coming from a salty company where we primarily dive the KM SL27 it was very hard to trust any other hat. But this KM 97 is fantastic. The ease of breathing is so substantial that diving long hours on our offshore rigs is nothing to tread about now. Only complaint is that it's a little front end heavy compared to the Superflow 350. But small price to pay for quality!