I expected something along the lines of a silk t shirt that would provide warmth as silk does.  This under shirt does provide some warmth at 55 to 60 degrees but don't think it will be much help when tempatures are at 50 degrees and lower.  The "silkweight dri release" in the description of the shirt sort of threw me off.  It is comfortable though and hugs the body well.  Have worn it under shirts while playing sports with no restricted movement in the arms and shoulders.