Review on Asus PRO Laptop AC Charger For P2540 And P2440 Series - Power Supply Adapter Cord Compatible With P2540UA, P2540UB, P2540UV, And More! by Marc Cahoon

The price was good, and I would have been pretty excited if this had actually worked for my P2540U laptop. At first it did seem like it might work because I didn't get the error messages I'd gotten when trying other models, but ultimately, I discovered that although it had the right type of connection, it didn't actually power the laptop or charge the battery, so I had to return it. Alas.