3 in 1 SIM gives the option for Micro, Nano or Standard Sim size. JUST ENSURE TO MAKE AT LEAST ONE CHARGABLE ACTION IN A SIX MONTH ROLLING PERIOD TO KEEP THE SIM CARD ACTIVE WITH O2. (3in1 SIM gives Nano/Micro/Standard option).
Official O2 Sim Card Classic Pay As You Go SIM Card – Standard/Micro/Nano UK
