Being able to swap your SIM card into a different phone is great -- until you find out it isn't the right size. If you need to fit your nano SIM into a micro SIM slot, the Sadapter can help.
I recently broke my phone, and promptly pulled out my old iPhone 4 as a temporary replacement -- only to find my nano SIM card wasn't compatible with its micro SIM slot. If you're getting a new phone, you can always just get a new SIM card, but this doesn't work if you just need it for a few days. (Similarly, you can always trim a card down, but you can't trim it back up).
Enter the Sadapter: a pack of three small SIM adaptors that fit your nano SIM into a micro SIM or regular SIM slot, or fit your Micro-SIM into a regular SIM slot. It's more expensive than other adaptors on the market, but it's less likely to get stuck or break.
I tested it in my iPhone 4, and it worked great. Just snap your SIM in the slot, then stick it into your phone. You may not think you need one now, but it's one of those tools that will probably come in handy one day -- so buy one and stick it in your toolbox now.
Sadapter Three Adaptor Pack [Amazon]