1. STRETCHABLE FUNCTION This plumb bob features an extendable function and can be adjusted by resistance to accommodate different sizes, ranging from 5 to 16 ounces. This allows for quick and stable balancing. Simply lift the plumb line gently, and the thread will automatically retract. 2. Easy to Use When using, maintain a reasonable distance parallel to the wall and pull the plumb bob downward to determine verticality. By measuring the distance between the ends of the cord and the wall, you can quickly determine whether the wall is vertical. In just a few simple steps, you'll obtain accurate measurement results. 3. VERSATILE This retractable plumb bob is suitable for decoration, construction, and many other applications. Whether you're a professional or an amateur, you can use it to precisely check verticality, greatly simplifying your workflow and improving efficiency. 4. Features: Users can choose between different specifications, from 150 grams to 400 grams, according to their needs. The lead weight can automatically and stably stop within seconds. When the positioning pin is not in use, place the safety lock in the 'ON' position to ensure allaround safe application.