Grip2u iPhone Case Review: Boost And Slim Cases Feature Signature Band To Prevent Drops The Grip2u Boost on an iPhone XR Who are the Grip2u Phone Cases for? The Grip2u line of cases are perfect for iPhone users who are concerned about their phone slipping out of their hands Grip2u cases have a band on the back for users to slip their fingers through The Grip2u Boost comes with a built-in kickstand for watching shows and movies Cell phones are expensive, delicate devices and nobody knows that better than cell phone case manufacturer Grip2u. Their entire line of products is dedicated to protecting cell phones while also making them easier to use thanks to the signature band found on the back of the case.