Hi, I have another question. I am looking at different keys of whistles to complement the one I already have in D. Is the F whistle a 3rd higher than the one in D or a 6th lower? I was wondering if it was really high and shrill or lower and more mellow. Thanks. Linda
You can find high F and low F whistles!
Yeah, it’s confusing. Most F’s you’ll find will be lower than a high-D whistle.
Many makers try to show this by calling them “alto F” or sometimes “low F”.
If it’s higher than a high D, it will almost certainly be called a “high F” or
“Soprano F”.
i have both the low f and the low d the d is great for slow tunes ect and sound s lovely
Linda,
Much of what will influence your decision is the type of music you plan to play. If you only plan to play Irish music (traditional, not “Celtic”), then you will be playing a D whistle nearly all the time, and maybe an occasional C whistle.
However, if you also plan to play stuff like “Celtic” music, “Renaissance” music, hymns, modern music, or music from other traditions, you will want to get whistles in as many keys as you can find, a condition known as “WhOA”. 
(Note: This condition also affects ITM players, except that they obtain loads of D whistles of different brands and materials.)
All this having been said, I think (someone please set me straight if I’m wrong) the break between “high” and “low” whistles is the key of A. I’ve seen “high” and “low” versions of every other key, but the only A whistle I’ve ever seen is the one between low G and the B-flat above it.
Yeap, I don’t think that it exists something like a high A (above high G), it’d be SO tiny, and SO shrill! I can’t even imagine it 
I agree with BlassBlower, if you want another key, maybe a C whistle would be an option. I find the Eb quite useful as well.
Linda,
High F is shrill and looks quite a bit shorter than your D. Low F is longer and lower.
Thanks, everybody. The whistle bug is already biting, and I only got my D Clark Meg for Christmas. Since I love and plan to play a wide variety of music, I will probably need a wide variety of whistles to play it all on 
I already have my eye on a rosewood high end whistle.
You’d think so, but I have a Gen high F that is actually pretty sweet-sounding.
I’ve got a Generation high F in nickel. The tuning is a little iffy on some notes, but for the most part, it’s a pretty nice-sounding whistle. Here’s a quick recording I made quite a while back, when I had only been playing for a little while:
http://www.whistlethis.com/index.php?content=YkdsemRHVnU%3D&utid=TlRjPQ%3D%3D
There’s a little distortion from the cheap microphone, but the whistle doesn’t really get shrill until the highest notes.
EDIT:
Forgot to mention I’ve also got a Gen high G in brass. It’s a bit more shrill, but not as bad as you’d think. However, it’s a bit hard to play because the holes are so close together.
Jason