While the standard compression seal for the R&R cylinders work perfectly fine, some people worry about the correct pressure to tighten the collar to and the possiblity that the collar may back off if not properly secured. 

With these new seals and seal bodies, you can upgrade to a high quality cup seal with low friction simply by screwing off the compression nut, removing the oring, and gluing the new body onto the bulkhead. 

Instructions: 
Unscrew the original compression nut
Remove the nut and the original silicone o-ring
Rough up the bulkhead with sandpaper where it meets the base of the original brass seal housing.
Apply a bead of medium or thick CA onto the base face of the new seal body
Slip the seal over the shaft, ensuring that you get no glue on the shaft or brass seal body
Press the new seal body firmly in place and let cure
Apply a drop of lubricating oil or grease to the shaft
Slip the cup seal over the shaft with the flat side facing your cylinder. Press it into place firmly using anything that is flat and will not cut or damage the seal surface.