What is the 3kg Dumbbells? The 3kg dumbbells provide the ideal way to help strengthen, shape & tone your upper body as well as helping to create muscle definition too. This 3kg dumbbell is also suited for those who are new to weight training & want to increase their strength. When can I use the 3kg Dumbbells? Use the 3kg dumbbells anytime at home to help strengthen & tone your upper body.