Manual presses are suited for softer fruit like ripe apples or currants. They work by pressing the fruit into a steel cylinder, crushing it and forcing the juice out through a pourous bag. The pressure is either generated by turning a screw, or through a hydraulic pump, sort of like a car jack in reverse. They are great for currants because the stems can remain on, eliminating the time-consuming step of manually removing the stems. For best results, the currants can be crushed by hand a bit before putting them into the bag.
You can see manual presses from our Czech partners here