1) Question posted under Jasco GE timers.Timer is otherwise not identified as type, model or brand.Certainly this information shows on product manual.
2) Copy following link to help identify timer and download possible manual:http://waterheatertimer.org/GE-timers-and-manuals.html
3) Upward operational temperature for digital timers usually ranges 120-155 F. So this should not be issue in garage until global warming eliminates all electronic gadgets, batteries, and seriously affects electric transmission lines from power plant.
4) Downward operational temperature for digital timers vary widely by type and model number of timer.Some become unreliable at freezing. Some last 1 month in freezing. Some are rated to zero F. Some rated minus 10-40 F.
5) Smart plan is analog timer instead of digital timer.http://waterheatertimer.org/Intermatic-timers-and-manuals.html#appliance
This type timer will operate on electric power, and not be affected by temperature fluctuations. However timing is not down-to-the-minute 7-day as with digital timers.Note appliance watt rating before buying timer.
6) Two-outlet plug-in timers are not 2-channel timers or 2 circuit.2-channel timer means that the timer can be programmed for two separate timing programs, with each timer program controlling separate load with separate schedule for each load.
7) Example 2-channel timer: Intermatic 1125 digital timer.Note operating temperature -40F to +155, making this especially hardened timer, with wide range timing applications excluding delay functions, But with 1 year limited warranty as is typical with most timers.http://waterheatertimer.org/pdf/024_ET1100-sell-sheet.pdf