I got the Viper America with a Apollo Bio-filter (swapped with the Eagle Sport for one dive) on it and seems like I was clearing the reg every third breath. The first time I dove with it I was good to go without the Bio-filter. The Eagle Sport I got and The Apeks ATX 50 both have the Bio-filters because they are dry. My question for the Viper Metal or Viper America is that does they both have humidifying features like Sherwood Oasis? I'm also thinking about purchasing the Metal.