It is almost inevitable that you would require one for your smartphone since most of their displays are vulnerable and prone to scratch and may easily break when running. However, you have to ensure that the type that you would buy from the market is the best quality regardless of the price at which it is sold.
The one that you buy at any point in your life should be scratch resistant, designed to provide you with an exceptional view of the contents of your screen and highly flexible with good adhesive properties to make it a proper fit on any type of device. Although it may still be vulnerable to scratches and cracks, this product can still act as your protective shield.