Because I stumbled on one great offer this 4GB SONY Memory Stick PRO DUO what the first Sony memory card I bought. And though the main reason that its price, after been using it for some time (at least 15-20 time rewritten it fully) it would be fair to say That the fully satisfied with its performance.
Though I own someother more expansive memory cards, SanDisk Mostly, read / write characteristics of SONY Memory Stick PRO DUO 4GB are quite good and with its silent decent Capacity This card is good choice for your spare, or even first, memory card.
Memory card comes with adapter on and it can be used with AVCHD recording devices, so but PS3 and other Sony products (PSP for example).
THEREFORE IF you need large capacity, reliable or spare memory stick I can fully recommend SONY Memory Stick PRO DUO product.