Although at this price I wasn't expecting to buy a whiz-bang product, I was hoping for more than a "patient" that belonged on an autopsy table. For all the help they provided, the instructions could just as well have been written in Urdu. The unit itself showed no signs of life. Not one of the LEDs so much as flickered.
Assuming that the LEDs had actually worked, the device might at least have served as Christmas tree ornament. When a roadside service truck came to my rescue, the technician was carrying a medium-size case with a charger-jump starter inside. Once it was attached to my battery -- a very simple procedure-- my car came to life.
I asked the tech where I could buy a unit similar to his. He suggested Walmart or Home Depot, adding that I should expect to pay $125 to $150. I have since done a lot of research on battery starters and found a number of potentially useful units for about $75. I suggest you do the same.