Review on GSM SIM Card for GPS Trackers - Pet Kid Senior Vehicle Tracking Devices - 30 Day Service with Roaming in US, Canada & Mexico by Fred Griffin

I bought this to use with a GPS tracker. You'll be stuck with the monthly bill, but it's only about $7 instead of $30 if you bought a T-Mobile product, for example. In any case, at the end of the month you lose what you don't use. The tracker hasn't worked for me yet, but it's not because of this SIM card. But be careful, they don't accept American Express. Also probably don't take KOA (Camp Grounds of America). It was a little problem for me. Enable automatic monthly billing.