This is a 3-in-1 SIM Card Adapter, a three small pieces of non-aging plastic that give you the ability to turn your nano or micro SIM into a card the next size up for your cellular project. This adapter is able to convert a nano sized SIM card to both micro and standard size and a micro sized SIM card to standard. Each adapter is easily removed from the harness by pushing it out with your fingers or by using a pair of snippers for a clean edge.
More and more of us have a phone that uses a micro-SIM. Conversely, most cellular dev boards use a standard SIM. This will allow you to adapt the SIM from your phone (assuming you have a GSM phone) to prototype your project without needing a 2nd data SIM.