Regardless of the brand of these small power pack jump starters, one thing that seems universally problematic is not the battery pack itself but rather the spring-clip jumper cables that are prone to breakage. As with many, many others these cable clamps are made primarily from plastic (not rubber coated metal like regular jumper cables) and are prone to breaking especially at the pivot pin.
On the positive side, at least today’s offering has a clamp with a metal pivot pin and not all-plastic like others I’ve seen but you still need to exercise some care and caution when using them. It is especially important not to pull the clamps off of the battery posts as the impact of the jaws when they snap shut may cause it to break prematurely.