Chalk wheel Mouse, ergonomicThe chalk wheel Mouse from the prym. ergonomics series is ideal for freehand marking and marking on all 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 after the sewing of the fabric. The level of chalk in the cartridge can always be seen through a window. Replacement chalk cartridges are available for ordering with white or yellow chalk