Packs of blades like this are very useful if you are new to reciprocating saws. You can try a wide variety of blades without spending a lot of jack. Then when you decide which ones  work for what you need you just replace  those blades. I don't personally buy multi blade packs except when I get a  new saw and they come with it. But if you don't really know what kind of  blades you like, try one of these. You can learn a lot with one project.