There are 3 steps to pick the right Auto(DC) Adapter:

(1) Finding the right "tips"- Different laptops have different connectors. You need the right tip for your laptop. This is very simply to find. Basically, Auto(DC) Adapter comprise of 2 ends. One end is male power outlet. You use this end to plug into wall power outlet. The other end is called "TIP" which you will plug this tip into the "DC IN" in your laptop.

Your laptop won't work on the wrong tip. You can only use the " matching Tips"

(2) Finding the right "output voltage"- Different laptops were designed to consume power varied by equipments such as CD-Rom, LCD size, CPU maker and CPU speed. You require to use the "matching voltage" . Only use the Auto(DC) Adapter output the matching voltage of your laptops. You can easily locate your laptop voltage. Mostly, voltage is printed on your laptops. You also can check your laptop manual.

(3) Find the right "input voltage"- for those users who will travel abroad especially to Europe and Asia. You would need Auto(DC) Adapter that Replacement with 220-240 voltage also.Always look for AC adapters accept 100~240 voltages.100~240 voltages AC adapters will go with you worldwide. You do not need to carry 2 adapters anymore!.

Better yet!AC adapter manufacturers are now promoting "universal AC adapters" .

This emerging adapters can be used with multiple devices. They can accept 100~240 input voltages and also adjust the output voltage to match device automatically.