After seeing these at £35:
I thought I'd have a look for them, and saw that the Stafford store had them on sale, listed at £50 on the shelf. I asked an assistant to scan the item, only to find that they have been reduced to £25!!
I can confirm that this is the 2.5 Portable version (powered by USB).
Manufacturers code - HD-PV500u2/BKhttp://www.buffalotech.com/products/portable-hard-drives/juststore-portable/juststore-portable-hd-pvu2/
Looks as though ASDA have not listed the item correctly on their system as the shelf label for the product lists item number 507353.
Worth calling your local store (I think that they're only in a limited number - & not online) and checking the product code 507353 and barcode 5060126038214
I bought three and left one unit at Stafford store (gotta spread the love, eh?), they may have had more in their warehouse?
Hard disk drive capacity: 500 GB
Hard disk rotational speed: -
Hard disk interface: Serial ATA
Hard disk size: -
PC and Mac compatible
Plug-n-Play - ready for immediate use
USB Powered - no power supply needed
Compact, lightweight in a black slim line chassis
Turbo USB for 20% faster data transfer rates
Windows® 7 (32/64-Bit)