This set contains 8 x 2.5kg weights, 4 x 1.25kg weights and 4 x 0.75kg weights (total 28kg). Each of the dumbbell bars weights 1kg.
2.5kg weights are each around 22cm in diameter and 4cm in thickness.
1.25kg weights are each around 18cm in diameter and 3cm in thickness.
0.75kg weights are each around 15.5cm in diameter and 2.5cm in thickness.
Each bar is about 49cm long.
Overall this makes the dumbbell set fairly bulky compared to cast iron dumbbells I've used before. This may present a problem for some people in terms of being able to pull the weight in close to their body, though this hasn't been much of an issue for me so far (I'm 6 ft tall and fairly skinny). Also the large size means the weight isn't as concentrated around a particular spot so this may affect how your muscles are trained, although I'm no expert on the science.
The spinlock collars are made of plastic but doesn't seem to be a problem so far.
The maximum weight you can load onto a single dumbbell is 17.5kg - 6 x 2.5kg, 2 x 1.25kg. Add on the 1kg of the bar's weight and that means a max. of 18.5kg - useful for one-armed curls. However stacking up all those weights like that means the dumbbell becomes ridiculously bulky.
Overall with this product you get what you pay for. 30kg of weights is fantastic, but the size is slightly impractical and everything is plastic-coated. If you don't mind that, then get this set as it's very good value per kg of weight - iron dumbbell sets of equivalent weight will probably set you back at least twice the amount.
Delivery was fairly prompt (8 days from Germany to here in the UK, from an estimated delivery time of 4 - 28 days).