There are good reviews for this product out there, search youtube for reviews and instructions for use.
Speed loader works great with surplus steel mags. It's a bit more tricky with Tapco polymer mags, because the loader doesn't fully seat onto the mag. But once you get the hang of it it's simple.
Bottom line, for the money this loader is a no brainier. If you have both a SKS and an AK keeping the ammo in strippers in a ammo can with desiccant packs is a good way to maintain your inventory. That way you can save your mag springs and not keep your ammo in boxes that can retain moisture.
Pros: Cheap easy to use
This review was written in the old system and had content requirements that are different than reviews written today.