These little yellow levels are a game-changer for any DIYer or pro working with string lines. The pack comes with 8 of them, so you can have a bunch on hand or share with a crew. Each one is small (about 75mm long) and super lightweight, so it won't weigh down your string and cause sag. The best part is the molded hook on the back – you just hang it right on your mason's line, builder's string, or any straight edge you're using as a guide. The bubble vial is made from clear acrylic so you can read it at a glance, telling you if your line is perfectly level. They're perfect for lining up bricks, tiles, setting pipes and drainage channels, or any project where you need a long, level reference line. Durable ABS plastic construction means they can handle the job site. A simple, affordable, and super effective tool to make sure your work is spot-on.