Comments about Scubapro C300 Regulator, Second Stage Only:

I had to purchase this because I needed the first stage, which I purchased separately. My old SeaQuest second stage had a different fitting, so I had to go ahead and get this. (Bummer, because it was so much more expensive to do it this way.) Due to one other review, I was concerned when it made a terrible noise when breathing on land! However, it was fine in the water and I had no problem. I did find the mouthpiece to be quite large and hard. I swapped it out after a few days of diving, but not before I had a swollen lip! (Stupid on my part, as the switch was not difficult!)

Comments about Scubapro C300 Regulator, Second Stage Only:

I have been spoiled by my Scubapro MK25/S600 first stage and second stage. This regulator is so smooth and effortless that I hardly know I'm using it.

I bought the MK17/C300 as a backup to my regulator and for my daughter to use on vacation. The first time I used the C600, I noticed a loud and annoying whistle on inhale. This was not an occasional problem. It happened every breath. The breathing is also substantially more labored than my MK25/S600. I know you get what you pay for, but the MK17/C300 is a marked disappointment. Next step is to contact LP and see about repair or replacement.

If this is an isolated problem, I find it difficult to believe that such an obvious and immediate problem made it past both Scubapro's and LP's quality check.