If you see these poorly-named,
bastardized Sony PlayStation accessories, no matter what the
temptation, do not
purchase one! They will be advertised to store an
ungodly number of pages (sets of 15 slots), say 25. You would think to yourself, "Wow,
self, this is great! I'll never be able to use up all those pages!"
Well, guess what? You'll never get a chance to use up all those pages! These things are cheap and rely on something nondeterministic -- data compression -- to store as much as it portends to. Not only that, but the compression estimate is incorrect, and you'll never get nearly the amount of storage specified.
When you go to switch pages on these devices, you may notice it takes a long time; this is because the current page is being compressed and stored and then the page you are switching to is being uncompressed. This is prone to failure because if the memory card is full, you will not be able to switch pages. The only solutions then would be (1) to delete slots on the current page, or, that probably being a bad thing, (2) get another memory card to swap things with. Either way, it's a tremendous pain in the arse.
A clearly poorly-thought out design for a subpar product; just buy regular, one-page memory cards. They won't fail like the "super" ones do and really, the price is not worse for the amount of storage you get.