i have been a long term user of extender devices. I used to us JES extender however switch to a vacuum type device in autoextender.
Just as a warning, i delevoped blisters when I used it, which is why it is advisable to use antiblister tape. However the blister came quite often even with the tape, and although they healed up, I seem to have developed a lack of sensitivity in my glans because of the constant blister. Something to be aware of!