Strong, high-visibility, stretch-resistant line and heavy duty L-shaped blocks for line positioning under tension. Blocks allow line storage. For marking out and bricklaying applications. Aids creation of straight, true and consistent courses. Strong, high-visibility, stretch-resistant line and heavy duty L-shaped blocks for line positioning under tension. Blocks allow line storage. For marking out and bricklaying applications. Aids creation of straight, true and consistent courses.