What size thread do you guys use when tying up marabou jigs? I have tied my own flies and have made a couple of marabous. I have been using thread left over from my fly tying kit, and some 2/0 floss that I purchased to tye up some clouser minnows, and i feel that the fly tying thread is too small (70) and the floss (2/0) is too large. I don't understand the number value of the threads. Can someone give me a hand with understanding it?

Thanks,

Eric Conley