Mine did come with a UK power adapter but I suspect this depends on the seller - I purchased from Cartridge Point. I have purchased items from Avides in the past (who I also note also sell this item and are based in Germany - always check the Detailed Seller Information!) and had European power adapters so that maybe why some purchasers have had an issue. It might be interesting to know the seller the previous reviewers purchased from. For anyone purchasing my box is marked Model No : DUB-H7, UPC Code 7 9006925237 2, H/W Ver: B1, there is no obvious -UK marking so you probably have to open the box to check the adapter type.
As for the unit - it is ideal for what I wanted - to connect 4 SD card readers to a single laptop USB port - the spacing between ports means I use every other one (the pitch is approx 11mm i.e. 5mm or so between the connectors) I have four Kingston Technology USB 3.0 Multi Card Reader
plugged in (with no requirement for an external PSU because they are low power devices) and they all work just fine.