Apparently I've owned mine for longer than I realized. They have a bunch of new models, and mine look a little different.
For semi-rescue charging and maintaining, I use the Batter Tender Plus (12V 1.25 Amp), SKU 021-0128:
> Battery Tender® Plus 12V, 1.25 AMP Battery Charger <
This will recover a flat battery in a matter of hours, and you don't need to worry about the amperage overpowering any size automotive battery.
For long-term maintenance, particularly on small (motorcycle) batteries, the Battery Tender Junior (12V 0.75 Amp), SKU 021-0123:
> Battery Tender® Junior 12V, 750mA Battery Charger <
This will take almost twice as long to recover a flat battery, but it is perfect for maintaining smaller motorcycle and lawn tractor batteries.
They also make a 6 volt / 12 volt selectable version of the Plus (1.25A) model, SKU 022-0211-DL-WH, in case you have any 6v cars:
Selectable 1.25 amp charger for both 12V and 6V batteries. Smart technology automatically adjusts charging stages. Universal solution for multiple battery types.
www.batterytender.com
They also have multi-bank versions of the 1.25A charger so you can charge your whole fleet with a single unit.