Used Centronics 50 pin male/male cables. Not tested, but passed a visual inspection. Centronics cables like this tend to be pretty robust, even if they are old and a bit dingy, as these are. This is one of many vintage items from a computer store that closed in the early 2000's. It has been carefully stored since that time- see my other listings for more items, including many in their original packaging! Thank you for stopping by. Have a great day!