Good measure; every curve machine quilting ruler set by Amanda murphy is a set of three 1/4" Thick rulers to be used as guides for machine quilting. Every curve Ruler set gives many different curve profiles based on circles with 6" - 12" Diameters works well with the every circle set which provide tighter curves set of 3 rulers have; markings that clearly indicate the previous row's Quilting lines, Not found on other ruler, not found on other rulers all have non-slip backing