Thank you for viewing. This is a very old product, so old that I can't even remember when or where I bought it. I found it while organizing my house. I will be selling it since I have no use for it anymore. MSP - 51 Pen Mouse W 24 x D141 x H28mm System: Serial Mouse Resolution: 256 counts / inch Encoder System: Optical Mechanical Buttons: 2 buttons Cable Length: 1.5m Compatible Models: IBM, PS/V series, various DOS/V machines Connector Type: D-sub 9-pin female adapter ; D-sub 9-pin male - Mini DIN 6-pin male included I am selling this as a completely junk item because I do not have an environment to test its functionality at this time (the ball moved smoothly when I touched it). Please consider purchasing with the understanding of this. Thank you.