Just clamp your dumbbells in. That's all it takes to turn them into a barbell. The bar is a flat, straight type. Compatible dumbbell diameter: 28mm~35mm, width is 100mm or more. *Cannot be attached to power block type dumbbells. The weight capacity is 90kg. Dumbbells up to 45kg can be attached to each side. There are no noticeable scratches or stains, but it has been in someone's possession before. Please refrain from purchasing if you are sensitive to used items. Non-slip rubber pads included (2 sizes) The original adhesive is weak, and one side is detached, so it is recommended to apply double-sided tape such as 3M.