If you've purchased an Android Register (13.5) which has mobile SIM capabilities and need some assistance in installing the SIM, do refer to the guide below!
How to insert a SIM card into the Android Register
Position the Android Register so the bottom is up or facing you.
In the designated SIM slot (refer to image below), insert your SIM card until it clicks into place.
How to eject the SIM card
To eject the SIM card, press the SIM card further in gently until it ejects. Remove the SIM card fully once it's been ejected.