2 Sizes: The package contains 6 pieces of dumbbell collars, including 4 pieces of spring lock collars with a 25 mm / 0.984 inch inner diameter for smooth barbell bars, and 2 pieces of dumbbell collars with a 24 mm / 0.945 inch inner diameter for threaded dumbbells. Different sizes are suitable for different dumbbells. Please check carefully before purchasing the size and type of your barbell. Quality Material: The spring clip collars are made of quality steel to ensure durability and reliability. They are rustproof and sturdy, not easy to break or deform, and can serve you for a long time. Easy to Hold: Each spring clip comes with a smooth handle that is easy and convenient to hold. The spring clip collar is also easier to attach and remove from the barbell, saving you effort and allowing for easy application. Safe Training: Our barbell collar can withstand significant weight and movement, making it ideal for weightlifting and strength training. Suitable for both home and fitness use, it helps ensure safety during fast and powerful training by preventing weights from shifting or suddenly dropping. Easy to Handle: The spring collars allow quick and easy adjustment of weight plates, securely holding dumbbells in place during lifting. They can be quickly loosened and fastened, allowing smooth sliding when changing weights.