This reply is a bit late, but I read a not-so-complimentary review of this thumb keyboard including comments that the keys were difficult to press and the driver that came with the keyboard was not 100 percent accurate.
As alternate, albeit larger than a thumb keyboard, there is an IR fold out keyboard
on eBay with a BIN of $36.99 currently available. I was just there and noted about 10 of them listed separately.