thats a complete valve.
you need just a actuator (top part)
http://www.heatingcontrolsonline.co.uk/acl-drayton-invensys-ma1-actuator-p-112.html
you need just a actuator (top part)
http://www.heatingcontrolsonline.co.uk/acl-drayton-invensys-ma1-actuator-p-112.html