Just read this article:
[url=http://www.flyfisherman.com/ftb/hwcdc/index.html:e17b1]http://www.flyfisherman.com/ftb/hwcdc/index.html[/url:e17b1]

that classifies CDC feathers type 1-4. Oiler puffs (type 3) can be purchased separately, but otherwise I think you have to examine the feathers to decide if you're buying types 1, 2, or 3.

This makes it tough to purchase over the internet, and I suspect the CDC I can purchase locally is mostly type 4. Right now, I'm mainly interested in tying the CDC & Elk in smaller sizes -- for which "type 1" CDC is recommended.

Where do you regular CDC tiers get your CDC?