Connecting Threads Essential thread is 50wt 3 ply cotton. It is good for piecing but can be linty which doesn't bother me. Connecting Threads Essential Pro is 70wt poly. It is strong and good for longarm machines. I use it in my bobbin for all sewing. It's good for piecing too as it is thin and strong and low lint. I have been sewing for years so I have used most all brands of thread. I don't have a favorite brand. I go by weight and ply.