Ironmaster Dumbbells, Kettlebells
Dumbbells are extremely versatile: they offer huge exercise variety, because they're used by each arm independently, they help repair of strength imbalances where barbells don't, and the arms-independent aspect means your core is automatically worked more than with barbells. These dumbbells are the best to train with. And they can convert instantly to a kettlebell set.
Replace a wall of regular dumbbells with these compact adjustables in a space 2 foot square. Larger sets come with a stand with inbuilt storage. And you can upgrade from the 2 to 20.4 kg (45 lb) set to the 34 kg and 54 kg (120 lb) set for the difference in price. (And go to 72 kg sets; people do this!)
They cost hundreds less than the equivalent in hex dumbbells, and they're nicer to use because they're more compact. There's little overhead clash during presses, because they're not bulky, for instance, and they're more maneuverable. And they're more of a reliable pleasure to use than common plastic-dial-driven adjustable dumbbells.
Ironmaster kettlebells use the same US-patented, instantly-dependable locking principle. Finally, adjusting from one weight to another happens in smaller increments, so with both kettlebells and dumbbells you get stronger faster and more smoothly.