In order to get serious about weight training, you are going to need a good set of weights. The Body Institute Multifunction Ring-shaped Dumbbells are worth a look. They are designed to replace dumbbells, kettlebells, and weight plates. You can use the center, side, or two-hand grip to push your body hard.
These dumbbells are made of cast iron, wrapped with frosted PVC exterior. They measure 18.5cm x 18.5cm.