It reduces the 'wings' temporarily, for a smoother upper arm look.
I have been wearing for a month now and have not noticed anything permenant, but while wearing it I look firmer under my fitted long sleave garments.
I wish I would have purchased the shorter sleave version as the cuff area shows on me and I am 5' 10"  and chubby so I have chunkier and longer than average arms.
It is fairly comfortable but binds a bit at the end of the day in the armpit region.