There are 3 different sizes: They fit 25mm, 28mm and 30mm diameter barbell bars, please confirm your equipment size before purchasing. Full Steel Construction: This spring clamps is made of high quality steel which firmly holds your weight bars. Its sturdy structure ensures superior functionality and improved durability, making this piece of equipment long-lasting. Safe and secure grip: Spring-loaded latch provides superior grip to hold plates in place, allowing for a more secure workout. Easy to Install: The comfortable and soft grip makes the spring clip easy to install and remove. Simply gently press the spring clip onto the workout gear and release. Wide Range of Use: The package comes with 6 pieces of dumbbell springs, enough can meet your training needs, and can also be applied to share with your friends. Note: The data is all manual measurement, please understand. Please allow 1 - 3cm error, due to the light and display difference, there will be some color difference, depending on the physical object received.