Welcome ! We have been one of the leading online suppliers of vacuum tubes for many years. Recently, we acquired a very large collection of tubes that we are excited to offer. We have tested and sold thousands of these tubes, and have many, many more to sell. After testing literally thousands of tubes from this collection, we have found only a small handful that did not test well. The vast majority tested strong. We will combine shipping on multiple purchases within 5 days of the first auction ending. Payment must be made within 5 days or your purchase will be canceled and re-listed. We do not have the space to hold onto auctions for you for any longer than this. If you would like combined shipping, please wait to make payment until after we have sent your invoice. We send invoices each day after all auctions have ended for that day. Combined shipping can only be combined with this shop, not other shops with similar names. Thank you for shopping with us! We have checked thousands of the individual boxes, almost every one we checked contained the right tube, There were only a couple that had the wrong tube in the box. These flats are sold as is.