Just a word of caution... while they are quite adaptable, they don't fit all cues perfectly.
I really like mine. It works like a charm but really on only one cue of mine... so when I need to use it I grab that cue. Not tryin' to knock anybody's business... just trying to share information with my pool brothers.
I have a Bob Frey SP that it fits perfectly... nice and snug. The diameter of the butt 4" up from the bumper is 1.20". I selected 4" because the extension slips on ~8" total. The butt diameter of this cue is 1.255" immediately above the bumper.
I also have a Bob Frey custom that it doesn't fit as well... it's a bit too loose. The butt diameter of that cue 4" up is 1.165". The butt diameter of this cue immediately above thew bumper is 1.210".
I also have a Dominiak custom that it won't slip all the way on... the butt is too big. The Hager only slips on for only ~2.5"... and it's butt diameter at 2" up is 1.265". However, it does fit tight and could be used.
I also have another SP that it doesn't fit very well... it's a bit too loose as well. It's butt diameter 4" up is just shy of 1.20". The butt diameter of this cue immediately above the bumper is 1.215... pretty thin.
So, it looks like there's a range of what it will fit well... just take note.
cd