These SIM adapters are ideal for people that regularly changing mobile phone. For my part, I have a Nano SIM card (that of the iphone) and thanks to these adapters can I test different GSM. For my job (head phone) is the ideal !! But I also used in the private setting where my SIM is also a NANO. The big advantages: change phone whenever you want. No need to wait for a new SIM. Pitfalls I see none for the moment!