Without this cutter, you need to cut the sim card by yourself. Firstly, you need to measure the sim card, remark part-lines on the card, then you hold a scissor to cut the card, you need to be careful to avoid broken the sim card. Many people had a try, it's high risk to broken the sim card.
With this cutter, all the measurement is accurately done for the cutter, you just need to input the SIM Card in correct way.
Professionally cut your regular sized SIM card to a micro SIM. Use the micro SIM in your iPhone 4 or iPad. This is 2nd generation sim cutter from Noosy. More reliable and reduce chance of failure. You can reuse the micro SIM in your old devices.