"Because manufacturers tend to heavily overcharge for replacement adapters a number of companies have started to sell them. Even if you haven't lost your power adapter it makes sense to have two so you can, for example, leave one at home and the other at the office. This will save a pound or so off of your travel equipment and allow you to actually appreciate that ultraportable. Antec has come out with a product that could benefit a lot of notebook users- a universal notebook adapter. In many ways the NP-100 is just your standard power adapter, but it will work almost any notebook and it's cheaper then buying from the manufacturer."