Reciprocating or reversing screw n nut
The screw is specially manufactured with a special nut to reciprocate at its travel ends.
RS1010-200 10mm pitch 200mm working length 400mm total
RS2020-250 20mm pitch 250mm working length 460mm total
RS2525-500 25mm pitch 500mm working length 700mm total
It's different with a normal lead screw or ball screw which is one direction no return running except you change the motor from CW to CCW vice versa.