These kinds of espresso makers - as you can tell from their name - work on a manual rather than automatic basis. So, instead of the coffee maker dictating how your espresso will come out, you take some of the control.
If you use a manual espresso maker then you basically control how your espresso coffee will be brewed. You do this by controlling the pump that exerts the pressure to make espresso (usually by use of a specific lever that works like a piston in the machine). Your average automatic espresso percolator will do this for you - which does take away some of the fun and means that you have less control over the end product!
Many espresso aficionados much prefer to use a manual espresso maker simply because they can control the coffee that is actually produced. So, as you become skilled, you can adjust the way your espresso is brewed and it's much easier to produce coffee to your own tastes with this kind of machine rather than with an automatic one.
It's very easy to get hold of this kind of espresso maker - you'll find that most of the major manufacturers such as Black & Decker, DeLonghi, Gaggia, Kenmore, Krups and Salton, for example, have produced this kind of machine. Don't think that a manual machine is not for domestic use - many people think that these machines can only be used properly by trained baristas but that just isn't the case anymore.
You do need to be aware, however, that this isn't the easiest way to brew a cup of espresso for all people at the beginning - that is, until you get used to working the machine. So, it's vital to make sure that you read reviews and user operating manuals as you go along. Remember that you'll probably need to experiment a little before you start producing the perfect cup of espresso for you - but it won't take you long to learn what works for you and you'll soon be brewing perfect espressos to suit your every mood with skill.
For more information on espress machines go here!