Good performance: These individual life rings are a good choice for anyone who needs a quality pulley for mountain rescue, tower work, ski tours or whatever. Essential to use: The black is mounted with ball bearings for higher efficiency, stability and smoothness, which is well proven in practice. Easy to install and remove: Remove the concave pulley and polishing treatment on the surface for easy and quick installation and rope. Better choice: For large loads, this large roll is much better and this product is 28KN for high durability to meet your needs.