The document describes the M-228 and M-229 series linear actuators from PI. It provides the following key details: - The actuators provide travel ranges of 10mm or 25mm using high-resolution stepper motors, and can push or pull loads up to 80N. - Models with gearhead/stepper motor combinations offer the same stroke in a more compact package. - Features include a non-rotating tip, limit and reference switches, and mechanical position display. - Advantages of the non-rotating tip design are listed.