Serial DB25 to DB9 adapter plug These are adapter plugs to adapt a db25 serial connector on a pc to a 9 pin connector. The common application on old pc's was to plug a 9 pin serial mouse into a 25 pin connector on your pc. Shipping will be added to your bid. Click on tab for shipping estimate to your zip code. Terms Conditions: California Residents please add sales tax. Small items will normally be shipped USPS, larger items Fedex Smartpost or Fedex Ground, please check shipping tab, different options may be available We do ship some items internationally, please inquire. A Handling charge may be added for international shipments. All sales final with no warranties unless stated otherwise.