I believe it is Nancy's Notions that carries a "Quilter's Chalk Line" but you can probably purchase a carpenter's chalk line at a 'home depot' type store then fill it with pounce powder or clover chalk (the refills from the clover chalk wheel markers would work for this) I wouldn't recommend using the chalk that carpenters use- unless you can test it first to make sure it's not going to stain- I use one I bought at the Ace Hardware & I put pounce powder in it- then I just brush off any still noticeable - but after squaring up the quilt any still there is on the edge anyway & would be inside the binding.