Reasonable price (8 EUR in my case) for the BT 4.0. This adapter may be a little too big and in some cases, prevent use of an adjacent USB port (USB key a little thick for example) => 1 star less. Do not especially try to install the software provided with (the downloaded site late March 2014 is not better); a large totally insoluble problem VB runtime prevents any installation! => 1 star less, an effort to "Cable Matters" would be welcome to correct this. Works under Windows 8.1 Pro 32bit recognized directly without drivers or software Runs Windows 7 Pro 64 bit after battling for drivers / software: I have clean (I should say eradicate) completely all the drivers and Bluetooth software on my machine (delicate and tedious but necessary process) before the adapter is recognized natively by Windows 7. Listed Bluetooth product is primarily used to play music on BT speakers: correct and sufficient scope for my use (~ 5 to 8m).