Review on Dell D5G6M 7.4mm to 4.5mm Dongle DC Power Converter Cable, Compatible with 57J49 and 331-9319 for M3800 XPS Series, Inspiron Series, and More by Matt Hamilton

Used to convert a Dell 90w charger with a larger port to work in flight with my 5510 and 5520 laptops as the factory 130w overrides the over voltage protection of the built in chargers destroy. Works perfectly. I wrapped some loops of tape around the connector to keep it from coming loose (I lost one) - it's not loose or anything, but this cable is so small that if you pull on it and break it, you can't to realize it's gone before it's too late.