The Festo ERMS-25-90-ST-M-H1-PLK-AA is a rotary drive unit — a motor unit accessory — designed to mount onto Festo's mini linear actuators in the EGSL, EGSC, and EGSS series. It delivers a 90° rotation at 24 V, with an 83 mm body length that keeps the assembly compact on the actuator carriage.
The 90° rotation and 24 V supply match the standard control voltage in most European and Asian panels. The 83 mm length governs how much carriage travel the actuator loses to the drive head — check your stroke budget before specifying. It's a motor unit, so it needs a separate controller or valve manifold to command the rotation; it's not a self-contained actuator.