The Hyperflex 50/50 longsleeve rash guard does what I ordered it for in reducing water exchange under my 5mm full wetsuit. It will also give me another layer of warmth under my half-mill skin on tropical dives. But I'm disappointed in its "hyperflex"-ability. I have shoulder issues and struggle to get in and out of my hooded vest. I had hoped a neoprene/poly rash guard would be easier to don and doff. Sadly, I have to ask a buddy to help me pull this thing off after dives. The core neoprene panels don't seem to flex at all, and the poly side panels don't flex enough. Even the neck is an uncomfortable squeeze going over my head. At the urging of an LP chat expert, I went one size up and ordered a large, but it was too loose in the chest. LP's PFF policy got me the medium I needed in just a few more days at no additional cost. And for some reason the price was $25 less than when I first started shopping! I'll hang on to this for cold water dives and as another layer for tropical dives when I'm traveling with just the skin, but I doubt I'll be using it as much as I had planned as my only exposure protection for surfing.