I am persnickidy about the quality of what I use. I really needed class 15 bobbins with nitches that hold the bobbin in tight during high speed filling of the bobbin. (I hate it when I have to cut a 100 yards of thread off a bobbin because it wound on loose -- and I can count on bobbin fauling up if I use it.) Love these bobbins! I experienced consistent great hold enabling tight winding of bobbin threads. No waste or mess. I am very happy with this. My complements to the manufacturer for a quality bobbin and to World Weidner for carrying this product. The easy snap on caps are helpful especially when I am rotating between thread colors. This way I don't have to keep putting the bobbins in the bobbin case during a project. Haven't needed to use the snap together feature yet, but had fun playing around with the many options in the use of the snaps. This feature will come in handy when I need it for my next grouping of rotating thread colors.