Card slots. A bottle opener. Pepper spray. Defense against a .50 caliber bullet. Whatever you might need on the go, people are thinking of ways for you to integrate it right into your iPhone case.But Y Combinator startup Graft Concepts is trying to cover all your basic needs with one case, using a simple latched frame and interchangeable backplates. Named Leverage, the case’s frame alone is meant to be a bumper for the phone and comes with either a plain backplate for $40 or a card holder (which fits about five cards) for $50. Additional backplates range from $7 to $30 based on design and material.