I bought 4 different shirts like this one based on their reviews.  This one fits me the best and is like a second skin.  Very comfortable.  As for sunblocking ability, I wore it on the boat on a fishing trip on a day where the temperatures were in the mid 90s and very sunny.  I never felt hot at all and noticed that night that my hands got sunburned beginning where this shirt ended.  Hmmm, maybe offer this shirt with back of hand coverage too?  Not an issue, just a thought.