Prym Parallel Tracing Wheel £10.15 Currently out of stock Fantastic tool for marking accurate lines like seam allowances or boning channels with ease! This gadget works by distributing a very thin line of loose chalk onto your fabric which is easily brushed away when you have finished your work. Curved lines are easy! This tool is a two part system featruing a main chalk wheel which distributes the chalk, and a tracing wheel which runs parallel and is combined with the adjustable measuring unit. Have a look at the video below for more info and a demo.