(3FF SIM)

3FF stands for 3rd Form Factor.

A physically smaller SIM card. The electric contacts and circuitry of a Micro-SIM are identical to that of a larger SIM card; the plastic part is simply smaller.

Because size is the only difference, it is possible to make a multi-size SIM card that can be used either as a larger SIM, or as a micro-SIM after breaking away a plastic ring.