15kg  Adjustable dumbbell set are made of iron sand mixture inside and PE plastic wrapped outside, which has no rust characteristics and also prevents floor wear. With it, you can exercise your muscles and enjoy the sweat of exercise whenever and wherever you want. Free weight barbell connector is made of plated connector layer + thickened shock absorbing layer combination. When you use large weights to build muscle, the connector bar fits your body and the shock absorber layer reduces the pressure of the weight on your body parts, making your exercise safer and more comfortable. The non-slip nut has thickened threads to effectively keep the dumbbell weight secure and prevent wobbling during exercise. Smooth and rounded grip design provides you with faster assembly and disassembly when you switch training modes, maintaining the pace of your own workout.