This appliance is similar in function to a traditional Italian espresso pot, also called ’‘Moka’" Maker or ‘’Caffettiere‘’.
A real crema (as produced by most electric espresso machines) cannot be achieved with such an espresso maker.
The reason for this is that the pressure with which the steam is pressed through the espresso powder is a maximum of 2 bar in espresso makers. To achieve a really good crema, at least 8 bar of pressure is required.