It is much cheaper to wear fitover sunglasses than wearing prescription sunglasses. People who want to wear prescription glasses together with sunglasses all the time, it is a better choice to wear fitover sunglasses rather than prescription sunglasses. Besides, it is much more convenient to wear fitover sunglasses because you don't have to switch between two pairs of glasses. However, if you wear your glasses only occasionally, fitover sunglasses are not suitable for you because there's an existing glasses pair and you should wear them all the time.