Manufacturers come out with new refrigerators every year and the most reliable company 5 years ago might be just average today. Also, every company will have good models and bad models so instead of focusing on which manufacturer to buy from, it's better to look at specific refrigerator models instead. Of course, best selling doesn't always mean best quality or most reliable.
Double stacked magazines give you about double the magazine capacity of single stacks, but they are slightly less reliable for two reasons. They are more prone to drop jumbles and the ammunition loses alignment and won't feed without fixing the problem.
The DSS1 has a dual spring system that allows tolerances in the pouch both sideways and front & back, allowing it to accommodate different 9mm single-stack magazines, such as the magazines for Ruger LC9s, Walther CCP, S&W Shield (both 9mm and .40cal), Walther PPS M2, Glock 43, Springfield XDS, Kahr9 and Similar others.