Any variety of size of linen can be used - I have used from 32- 40ct. What can I say? I am obsessed? They are fun and relaxing for me. so much of what I do is for events with deadlines, for specific release dates... everything seems to be time sensitive and these are pure pleasure for me. With my love of specialty stitches and pattern and colour all in one little fun quick stitch for me, it is a must! They all have the silk threads, and wool felt backing in them for a reasonable price. Collect them all!