Chacopen Blue Water Soluble Dual Tip Pen With Eraser
https://www.cactusquiltshop.com/shop/5013cv-chacopen-blue-water-soluble-dual-tip-pen-with-eraser-9362
https://www.cactusquiltshop.com/web/image/product.template/9362/image_1920?unique=a56b997
Great for patchwork, quilting and sewing.