He compares car jump starters (like NOCO versus no name ones) to see which ones work.
They're an excellent tool to have in a car kit, you don't need someone else to jumpstart if you need to and being lithium ion based they hold their charge for a long time compared to the bigger lead acid ones that will die if not maintained.
They also often also serve as an external battery bank, 12V outlet / etc but I've never needed to use those features.
I ended up going with a "Topvision" brand because it seems to punch above its weight with regards to starting bigger engines like V8, have definitely gotten use out of it.