A Baker's Dozen when ordering. The backs are a wire eye loop which is ideal for sewing.
20L - 1/2" or 13MM ---------- 24L - 5/8" or 16MM ---------- 30L - 3/4" or 19MM
36L - 7/8" or 22MM ---------- 45L - 1 1/8" or 28MM ---------- 60L - 1 1/2" or 38MM
Note: - Do not forget to add your assembly tool.