Have worn many thermals over the years and this one was just weird - the body was true to size but the sleeves were not tight fitting AND very large under the armholes - just an odd shape

IT WORKS!  LIKE WEARING A THERMO WHEN IT IS COOL., I  USE MINE IN AN OUTDOOR POOL WHEN THE WEATHER COOLS, ESPECIALLY FOR A BREEZE/WIND THAT COMES ACROSS THE SURFACE.  KEEPS MY ARMS/TORSO WARM. 50-60 IS A GOOD TEMP RANGE . ARMS ARE LONG/JUST ROLL IT UP. GOOD FLEXIBLE UPPER ARMS FOR STROKING. TORSO IS LONG/ KEEPS THE HIPS WARM/STAYS PUT TOO.  YES, YOU SWIM SLOWER, BUT SO WHAT IF YOU ARE WARMER WHILE YOU ARE DOING IT.  IF YOU GET TOO WARM AFTER 50+ LAPS, TAKE IT OFF NO BIGGIE!  IT'S GETTING YOU IN THERE/STARTED THAT COUNT.
REMEMBER IT SHOULD BE WETSUIT SNUG.

I hate cold water. This is a lot easier than a wetsuit though not as warm.

I am a long time ocean swimmer-50+ yrs.  I do not like wetsuits and this is my  solution.  Water at our beach is running about 54 right now.  This is the 4th therma. type rash guard I have purchased.  One was for a gift.  The others were fuzzier inside and gave me plenty of  'core' protection.  The outer layer of this one seems sturdier but the inside does not have the polar type fuzz the others did.  It fits-I wore it - but I came out shivering.I will use it since I can't find an equivilent shirt., but I am sorry you changed the fabric

Great! Very happy with rash guard. Keeps cold out, easy to move around in, very light weight.
Would highly recommend it.

Good:
Very warm.
Great shoulder and arm movement.
High quality.

Bad:
Small and tight. I'm a size L and ordered an XL, but the fit is extremely tight, more like a Medium.

Heavy. That 8 oz. weight keeps you warm but it feels like wearing chain mail in the water.

Extremely itchy. The outer side of the fabric is a nice smooth spandex. The inner side, the part that grips your skin, is unusually rough fabric (polyolefin). Combine that with the small fit and it's "get this off me!" uncomfortable.


Conclusion:

Not worth the high cost. I have another O'Neil rash guard of the lighter spandex variety and they're smooth on the skin and very comfortable. Buy a couple of those and wear layers if you need the extra warmth. You can get 2 or 3 normal rash guards for the price of 1 of these thermo.