I get them here:
http://www.quiltersparadiseonline.co...menu-3300.html
I have *a lot* of thread, and I find these to be the best i have used. I have tried a lot of different storage units, but i really like these. They have handles, secure latches, and i can keep my threads very organized according to color.
They also make them for cone threads and Ingrid (store owner) can get them for you if you need them.
Hope this helps!