The correct SIM card for the LAMAX WatchY2 is: MicroSIM with dimensions 15.0 × 12.0 × 0.76 mm and for the LAMAX GPS Locator: NanoSIM with dimensions 8.8 x 12.3 x 0.76 mm.
You only need to insert a SIM card into the watch. You can use any prepaid card for the LAMAX Tracking device or mobile tariff, which include at least 30 MB of data per month. Free or paid minutes are entirely at your own discretion.