New Delhi, Nov. 18 -- Screen guards are the first line of defence for your phone or tablet. They face all the scratches and grime that could ruin your display but most people forget that they aren't designed to last forever. Many people install a screen guard on day one and only think about changing it after a serious drop but waiting that long can mean you miss the protection you paid for.

How do you know when your screen guard needs replacing? The first signs are naturally scratches and small cracks. You shouldn't ignore these main warning signs as even good-quality glass guards will pick up fine scratches from coins and keys in your pocket. It's important to note that plastic protectors scratch faster and will make your screens look h...