B grade should mean operational but will have visible signs of use, I would avoid and buy on ebay probably get a nearly new one that hasn't been through the hands of muppits

B grade is considered as looking used. So for example, it may have some wear and tear marks on, however, nothing major that will affect the use of the product. Furthermore, an item is considered a B grade, if the product does not have its original box. With the product that you are enquiring about, this may have some marks on the product, or, it may not have its original box, it will still have to come with everything that is required for the product to work. I hope that I have managed to help you and anyone else regarding grading.

A grade= practically new, should not have any scratches or damage to the product and MUST have all of it's original accessories.

B grade= General wear and tear marks of a used product, may not have its original accessories as these are not always require, unless the product in question needs them to allow it to function properly.

C grade= heavy scratches to the product, it may not have its original accessories.