Most any thread will work. Aurifill is good but not necessarily the best. I have used all kinds including old thread in my Bernina and they work great. the suggestion about cost per yd or foot is a good one and is really economical in the long run to get the larger spools in those colors that you use the most of - light gray, white, off white, beige, etc. I have a friend who pieces with light gray and uses a large cone. don't let the shop secuce you into believing "there's is the only one". This has happened to me when I needed just a little of a color and bought a large spool that I used one time. The local quilt shop is a dumping spot for sewers and quilters cleaning out their threa