The stationary carbon flange is attached to the front side of the bellow with hose clamps, and the back end of the bellow fits over the Stern tube and is secured with hose clamps. 
The stainless-steel rotor is fit on the shaft in front of the carbon flange. The stainless-steel rotor is used to compress the bellow before the rotor is secured to the shaft with set-screws. 
This compression (pre-load) maintains constant contact between the two flat faces of the stainless-steel rotor and carbon flange, allowing the PSS to compensate for the variable fore and aft movement due to propeller thrust. 
The carbon flange is over-bored to the shaft diameter allowing it to “float” around the shaft and thus compensate for most misalignment and vibration problems. 
The stainless-steel rotor is sealed to the shaft by two O-rings that are recessed into the bore of the collar. 
These O-rings rotate with the shaft and stainless-steel rotor and do not experience wear during operation.

You will need to select your shaft diameter and the outside diameter of your stern tube (shaft log).