The Irwin 3‑inch Plastic Line Level (model 1794483) is a lightweight, durable tool crafted from high-impact ABS plastic, designed to easily snap onto String or Chalk Lines via its open hooks. Its compact 3‑inch size and clear, easy-to-read vial make it ideal for quickly establishing level reference lines in layout and carpentry work. Durable open hooks to slide on the line. Allows you to level and layout string and can be used on chalk reels to snap a level line.