A-stock products are brand new. B-stock products are returns from customers or used to be showroom models. The box has been opened up before, but the product is still in new condition and fully functional. Before Thomann sends it out, it will be reviewed by their service center and you will receive a 3-year warranty with it as well as a 30-day money-back guarantee. If you want to save a buck or two, a B-stock product might be the perfect choice for you - without any risk at all!