If it's spun polyester thread, it's the cheapest and not very nice thread you can get(I'm trying to be nice). It's made to be used in many layers-like 4 or 5 threads on a serger to be strong enough for use. I would be very careful how you use it as serger thread is not a good thread for piecing or quilting because it's weak. Hopefully it's not a spun poly.