These types of dumbbells are the most common for home and commercial gyms. This guide will help you navigate among the advantages and disadvantages of each.
Hex dumbbells are made with chromed solid steel handles and welded-on cast iron heads with a painted finish. They’re typically found in home gyms and in some smaller fitness establishments.
Rubber hex dumbbells are the same as the above, with steel handles and iron heads, but with a rubber coating instead of paint. So while they are really just rubber coated, we call them rubber dumbbells for simplicity.
Pro style dumbbells are found in most commercial gyms. They’re made using solid steel handles and standard “pancake” style weight plates. They differ from standard adjustable dumbbells in that the handle ends are a precise length to fit an exact number of plates, it’s bolted together so as to be semi-permanent, and they usually have end caps to further smoothen out the edges.
Rubber pro style dumbbells are the above with rubber coating on the attached weight plates instead of paint. Again, for short we call them rubber rather than rubber coated. Keep in mind that regular pro style dumbbells can also be made with only rubber end caps.
All types above can have contoured handles rather than straight. Contoured handles are thicker in the center than the edges, making for a wider and more ergonomic grip.