It does the job! Cut an old T-Mobile SIM down to microSIM proportions. The fit is really close with the microSIM tray on iPhone 4 so you have to use your thumb to click the newly created microSIMs into the tray, but it will ensure a very secure contact and no wiggling in the phone. You have to give the stapler a good squeeze to get a clean cut, and normally after it pops out the microSIM result, the stapler is stuck and you should manually pull the top part back up before you can slide out the remains. Not a big deal, however. Also, I'd recommend getting micro SIM to SIM card adapters because the two plastic ones included are so flimsy and could not easily fit in my iPhone 3GS I tested them with. With other SIM phones, I doubt they'd be a problem but last thing you'd want if you're going back and forth between iPad/iPhone 4 and a previous gen iPhone is for the adapter to get stuck and have to take the phone apart to get it out. If you don't want to invest in "micro SIM to SIM card adapters," save the remains of the original SIM card (to the left in the picture) and pop the microsim back in there, then secure it with a layer of scotch tape to make sure it doesn't fall out. That should do the trick and work as if you didn't cut it at all. Anyways, this will be a great companion for when I go to Europe soon. I don't have a lot of faith in there being an abundance of prepaid microSIM cards at carrier stores. Also, last thing I want to do is mess up a prepaid SIM card after filing and cutting it manually, only to have to buy another prepaid plan. This is a good on-the-go solution.