Mini-SIM (2FF) SIM cards were introduced in 1996 and have the same contact arrangement as the full-size (1FF) SIM card. The 2FF 'mini-SIM' is distinctly smaller in size than the Full-size SIM with dimensions of 25.00 mm × 15.00 mm × 0.76 mm. Some networks refer to the 2FF mini-SIM as the Standard SIM or Regular SIM.
This also happens to currently be the size SIM card that most of our range of tough phones accept, whether they are single-SIM or dual-SIM devices.