I have a custom extension from APIC. Runs ~27" - ~78", I forget the exact dimensions. Love it. Cost about $80 few years ago. Well worth the cash, for me -- at the time, all the other extensions I found were either not long enough when extended, or too long when closed. (The Bogen extension comes closest and is probably what I'd get if I bought today with slightly different closed-length requirements.)
For something shorter, like the original linked item, I prefer a gooseneck like the ~21"
Bogen Heavy Duty Flex Arm. More flexible, literally and figuratively.
The original linked item looks like an On-Stage boom component. So you might also consider the
On Stage Posi-Lok Boom Kit, which comes with 7", 13", and 18" extensions + the posi-lok clutch. They also make fixed-length options, though I like the flexibility of the different extension lengths, either individually or attached to one another. And the clutch is helpful for altering placement from the stand base or clamping point.