Usage Tips:High quality Comprehensive Package for User Convenience: each package comes with 4 half circles, which can let you install into 2 pieces of ball stoppers, 4 screws, and 4 nuts, this completeness not only provides that you have the necessary things for installation but also have the convenience of use. Product Dimensions: the air hose stopper has a diameter of the center hole of about 0.77 inch (19.5mm), an outer diameter of about 2.99 inches (76mm), and a thickness of about 37.5mm, they are designed to work well with 1/2Inch ID hose reels and hoses with the outer diameters range from 0.75 inch/19 mm to 0.87 inch/22 mm, this feature simplifies setup and provides usage flexibility, and if the outside diameter of hose is small, you can tight the screws to make them stand firmly. Easy to Install: the air hose ball stop is easy and convenient to install, you can adjust these balls to the suitable places, then insert the included screw and tighten the nuts, which are easy to this job, 't take you so much time and energy, they can be applied to the automatic rewinding retractable hose reel and alternative spring-driven air hose reel, convenient to use. Rubber Material: the auto rewind air hose reel stopper is made of rubber material, this material offers durability, ensuring long lasting use, and the anti slip feature can let you hold them easily, 't slip down easily. Adjustable Positioning for Precise Control: featuring adjustable half circles, the hose reel stop allows for adjusting, they can be adjusted and fixed to exact positions to control the length and tension of your hose, providing a precise and controlled operation. Please note:the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:Black Material:rubber Package Contents: 4 * half circles 4 * screws 4 * nuts Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.