I did buy one last year after its was mentioned on here before (might have been you ?) but i struggle to get it fit tight enough. I ordered to correct "tighter" one and don't consider myself lacking in the girth department :-). So it might be just a case of me needing a bit more help. Best thiong i have found it the Durex one but fitted over everthing "balls and all" not sure if this how it caan be used but it seems to work well for me, fiddly to put on with the occasional mishap where one goes one side and the other goes the other if you get my drift , but so far so good.
Had the firmtech fitted tighter i could see it being much easier/comfortable to use