You can look through similar reviews (mostly from the other page selling the single pack of this product
Memory Stick Pro / Pro Duo Memory Card to USB 2.0 Adapter, Clear Blue) that all talk about how you shouldn't buy this products because it is cheaply made. I can't disagree with that, but just because it feels cheap doesn't mean it is junk.
First, you are getting 2 readers for less than 4 dollars, that is less than $2 a reader, so the cheap feel is kind of a given. Secondly, as other reviews put it, they can break if you man handle them. Third, and probably the most important, you probably aren't buying this product for the quality of the plastic as much as you are to read a memory stick, which it does do flawlessly. It is very easy to use; just place a memory stick in the reader and plug it into a USB port; No drivers needed [at least for Windows XP or later; I can't speak for other operating systems, but if your system knows what a USB drive is, then it should recognize this.]
This may sound like a rave review, but I do have some other comments as well. First, I use this as just a memory stick reader for my camera's memory stick. This reader sits in my bag and is only used about once a week to copy and delete pictures off of my stick. I do not use it as a full time USB drive replacement. If you plan of carrying it around as a USB drive that you use numerous times a day, I probably can't recommend it. Second, it is cheaply made, if you like substance to your items or have trouble handling things gently, go for a brand name.
I basically recommend this to the person that will use it for reading/writing to a memory stick used in a device, that doesn't plan on using it daily, looking of an inexpensive choice, and that doesn't have a track record with breaking things.