The base is molded into the body of the actuator. it is a short round stud, about 1/2" in diameter and maybe 3/4" in length (I don't have one in front of me at the moment). There is a 1/4" hold drilled for a steel pin which is oriented horizontally as the actuator is shown in the photo. The appearance of the stud molded into the base is nearly identical to the end you CAN see in the photo.
It should be noted that the actuator arm is threaded onto a screw shaft. It is screwed on with about one inch of threads. You can adjust the static length of the actuator by about 1/4" by screwing the arm out 1/2 rotation, or a full rotation, however, by unscrewing the shaft, you are probably reducing the rated load capacity because internally you have that many LESS threads holding the arm to the internal screw.












