Several points to understand when buying an Electric Vehicle Supply Equipment (EVSE) device.
First off, the EVSE is really nothing more than an extension cord that carries the electricity from behind the wall to the car. It isn't really a "charger". The charger is in your car. (Before someone blows a gasket, I realize that an EVSE is more than an extension cord. But for the purpose of this discussion, to think of it as only an extension cord will suffice.)
There are two things that effect the rate at which you can charge your car, the rated capacity of the EVSE and the rated capacity of the car's charger. Whichever of those two devices has the lower rating is the limit on how quickly you can charge. So, you need to know several numbers to take full advantage of the available resources in order to get the most from charging your vehicle.
1. What is the rated capacity of the charger in your vehicle?
2. How large of a circuit can you install in your home for the EVSE?
According to the Clipper Creek website, a Chevy Bolt has a 7.2 kWh charger installed in it. So, to get to 7.2 KWhs, you need an EVSE with a minimum rating of 32 amps to get the fastest charge on a Bolt. 32 amps multiplied by 240 volts equals 7.68 kWh.
To install a 32 amp EVSE in your home, you will need a 40 amp circuit breaker. Per the National Electrical Code (NEC), to operate a 32 amp device on a circuit, you must have a fuse/breaker rated at 125% of the load. That means 32 amps multiplied by 125% equals 40 amps.
You can buy any size EVSE you want. If you buy one that is rated less than 32 amps, then it will take longer to charge your car because the "extension cord" isn't capable of passing all the electricity to the car that it can take. On the other hand, you can buy an EVSE rated higher than 32 amps. You won't charge your Bolt with it's 7.2 kWh charger any quicker, but if you were to buy a car with a larger charger in the future, you would not need to upgrade your EVSE.