THOMPSON TEESweatproof Undershirt for Men with Underarm Sweat Pads (Original Fit, V-Neck)

usually for undershirts i wear L and thats pretty fitted and xl is a little to big any recommendations on the size i should i get this shirt ?

So it just keeps sweat from coming through your armpits? B/c I sweat a lot from my back

Hi, i am interested in purchasing a shirt. i have a small body frame so i'll purchase a size small, but my question is how often can i wear the shirt?

Are these good for wearing under normal t shirt, not just dress shirt?