The full-size SIM (or 1FF, 1st form factor) was the first form factor to appear. It has the size of a credit card (85.60 mm × 53.98 mm × 0.76 mm). Later smaller SIMs are often supplied embedded in a full-size card that they can be pushed out of.
The mini-SIM (or 2FF) card has the same contact arrangement as the full-size SIM card and is normally supplied within a full-size card carrier, attached by a number of linking pieces. This arrangement (defined in ISO/IEC 7810 as ID-1/00 lets such a card be used in a device that requires a full-size card – or in a device that requires a mini-SIM card, after breaking the linking pieces. As the full-size SIM is no longer used, some suppliers refer to the mini-SIM as a "standard SIM" or "regular SIM".
The micro-SIM was introduced by the European Telecommunications Standards Institute (ETSI) along with SCP, 3GPP (UTR)
The micro-SIM (or 3FF) card has the same thickness and contact arAN/GERAN), 3GPP2 (CDMA200, ARIB, GSM Association (GSMA SCaG and GSMNA), GlobalPlatform, Liberty Alliance, and the Open Mobile Alliance (OMA) for the purpose of fitting into devices too small for a mini-SIM card.