HP Upgrade Bay (compare AU097AA, AK868AA )
[HP12-2BAY-8730]

Great product, quality is excellent, over my expectations. Enpacking is also perfect. I have chosen the cheapest delivery (USPS), arrived to Hungary with no problems in a reasonable time.
Installation was easy, perfectly fits into my 8540.
The blue LED indicator lights a bit strong for me, so I'll band or cover it, but that's all I should do with. I can only recommend to anyone.