WW,

I like to use the guard hairs from rabbit or artic fox for my collars- flies last a little longer. However, I ocassionally use marabou for my spey flies. Rabbit collars will look very bulky when dry, but when fished, they thin down a lot and provided superb action... If you need examples, check out:
Steelheader.net

Top 5 flies are mine. They are tied Ed Haas style- indestructible! Email me if you have any questions (email address is in my profile).

Hope this helps!

Downriggin'
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"If you are not scratchin bottom, you ain't fishing deep enough!" -DR

Puget Sound Anglers, Gig Harbor Chapter