Well, probably more measurements than review. @rhythmdevils already covered this here: https://www.superbestaudiofriends.org/index.php?threads/40-dynamic-iem’s-that-sound-good-and-are-waterproof-to-12-feet-indefinitely.9569/ And I've finally gotten to this months after the fact. Thank you for your patience. The move from CA to TX was big and it took me months to move into a new place and get my measurement gear set up again. Anyway, not only are these IEMs neutralish, but also quite good sounding. Technically much better than their $40 price. The downsides are their rather non-impressive (but waterproof) construction and less than stellar channel matching. However from a clarity point of view, these are very good, better than some IEMs costing thousands and thousands of dollars. The lower to middle midrange sounds flat to my ears. The lows do sound slightly elevated. Bass texture is surprisingly evident. There isn't much pinna gain built-in, which is fine by me. On the other hand, the 2-3kHz region isn't depressed either. There is a dip around 5kHz (subjective and objective) that takes the edge off of snare drums and bite out of trumpets. The lower and mid treble are about right, but high treble, last octave air is missing. I really cannot complain for $40. Besides many single driver DD IEMs, even some high-end ones, lack air as well. H20 Surge Frequency Response (CS/SBAF comp) The measured peak near 8kHz is a measurement artifact from my coupler. H20 Surge (BLU/RED) vs GAudio Nair* (GRY) Frequency Response *Gaudio Nair IEM: consensus view by the Masters of the IEM Universe as the most neutral IEM evar. Note that Sean Olive does not belong in this club because he is deaf and actually a malign influence to good sound. Think of him as audio Darkseid. Then again, it's also been said in some circles that @rhythmdevils is deaf because he is white and lives in the USA.