String liner mason's line is durable 18 nylon in either twisted or braided varieties in a wide range of bright solid colors. We also offer "bonded" replacement line in braided, mixed color combinations in both 18 and 27 nylon. "Bonded" line has an additional coating which makes the twine stiffer and more abrasion resistant. It won't fray as easily when cut and it's easier to knot. The coating also helps to make the line more water, UV and rot resistant.