A4Accessories Sim Card Adapter / Converter / Storage For Standard Sim, Micro Sim and Nano Sim, With iPhone Sim Release Pin, in Credit Card Size (Red/Black)

Does the job. Not sure about it being small enough to carry around as it's quite thick. The adapters themselves are very good quality and don't snag on the SIM contacts like some cheaper ones can (which can cause permanent damage to your phone). The SIM tray tool is also very useful, nice to have it built-in. All in all a decent product.

Bought this because I travel a lot and have various SIM cards from foreign countries that I need to keep. This isn't a great solution as it actually only holds a couple of the smallest cards that are most common and easiest to lose. Why can't someone make an effective SIM storage device???