We do not accept returns for any reasons unless the products are "Dead on Arrival."
The CAN hardware products are described at http://canusb.com and http://can232.com. These are sensitive electronic components, and we cannot warranty against any misuse / use outside of the specifications.
We do not generally accept Purchase Orders with Net-XX terms, as we have had experiences with non-payment. We accept payments made by credit card through the secure web server on this site, or via a check drawn on a reputable USA Bank. You may enter a PO# when you check out, and we will reference that on the invoice.