SKD61.9 Electrohydraulic actuator, AC 24 V, DC 0...10 V, 700 N without spring return, 20 mm stroke. 
Key data to replacement product: Electrohydraulic actuator SKD60, AC 24 V, DC 0...10 V, 1000 N, 20 mm, similar functionality plus enhanced performance. 
Info: Operation with frost protection monitor QAF21.. or QAF61.. or remote setting unit FZA21.. requires SKD62UA (with spring return).