I have this one. Used it a whole bunch of times on my bike and others.
Shipped our bikes from South America to Europe, but due to multiple FUs, the shipping took over a month to get there and one of the batteries was DOA at the cargo dock in Croatia. Thankfully, had one of these and the bike started up no problem. The warehouse guys were all crowding around me watching me jump the bike with this tiny handheld device and they were all marveling at the technology like it was magic.
Even when not traveling, I still find it useful. Our school bikes are easy to bump start, but when the students bring their own bikes, sometimes the larger displacement bikes are harder to bump start, so this alleviates a lot of sweat and tears. Jumped an RC8 the other day no problem.
One caveat is to check every once in a while to make sure the thing is fully charged. They hold their charge for many, many months, but if you don't use it in over a year, it might be low or empty when you go to fish it out of your toolkit.
DAMHIK...
I usually top it up at the beginning of each riding season regardless of if I've used it or not.