This type of lever as shown on the link, is normally fitted in-line with racing type handle-bar brake levers, often to be found on touring bikes it allow you to keep your hands up / change position rather than always being on the drops.

To install the brake cable passes through this type of lever as well, to fit them the inner cable is pulled out, the outer cable cut, then the inner cable goes back in again.

Many years ago the older type of touring levers worked off from the normal brake levers but had an extended arm that came back up to the same place as shown on your link, this type as shown is a more modern version.

I've not personally seen the type on the link used on their own before ? I could not comment if you have the full braking leverage if the type on your link is used on their own ?