I am assuming your calling predators. I found calling to be a lot like fly fishing some days anything works and others it's the fly you just lost that was the only thing catching. The Knight and Hale is a good start but be prepared to experiment until you find something that works for you.
likely you will eventually have 6-12 different ones. Ask the guys at the shops what has been selling. Myself I like variable pitch but I have a couple of fixed pitch on my lanyard right now (I carry 4 at a time) they were on sale and came with a 3 spot lanyard oddly enough they worked but I was really after the lanyard.
For me out west here there are two sounds that I use Assorted Bunny or a howler. For you in the east I understand there are more types of sounds available to use but the rabbit will get you started.
