Watch an episode of "THE ANDY GRIFFITH SHOW". Check out the belt that Barney is wearing. You will see a leather item with what appears to be two sets of snaps, upper and lower. That is a old-style bullet holder for police.
The Speed Strip was invented at a time when those holders were still in use. The double snap one worked from top to bottom. Load from the top with six rounds per pouch, and take them out from the bottom when you needed them. There were also pouches with one snap on the top where the pouch itself fell outwards to let the cartridges drop out.
With the invention of the speed strip, you did not need to have the bottom drop pouch or the dropping pouch. The strip went into the holders neat as can be with the six rounds on them. I know, I used them.
As others have said, they are really not a speedy thing, nowadays, since the advent of HKS and Safariland speedloaders, but they were faster than dumping the cartridges into your palm. Two at a time is about as fast as you can get. And, as another posted said here, practice, practice, practice.
I still have mine, but I have some of those modern whizbangs, too!
The Doc is out now.