The specs on the charger are the specs you need to run and charge your laptop. The same specs. Not less or more. Choosing to use something that puts out the wrong amount of power can damage your laptop.
You should be getting the same one from Sony or a Sony dealer. To be honest. While aftermarket ones can work, it is also hit or miss with them. Alas, many say they have the same specs but in the end don't. So while you can choose an aftermarket one, just be careful as it may not work correctly, or last long.