Prym Ergonomic Chalk Wheel Mouse. The chalk wheel “Mouse” from the Prym.ergonomics series is ideal for freehand marking on all types of fabrics. The fine gear at the top of the mouse shaped chalk wheel leaves a clearly visible fine chalk line, which can be removed easily by brushing or washing. The level of chalk in the cartridge can always be seen through a window. Replacement chalk cartridges are available. The pleasant-to-hold ergonomic housing of the chalk mouse ensures fatigue free work. A grippy cap reliably closes the chalk wheel. It is no coincidence that this practical chalk wheel was awarded the Red Dot Design Award in 2010. Washable dressmaker’s chalk in powder form.