3 to 100 lb. $1.29/lb. Rounded edges of the heads provide more durability and comfort. Contoured handles give a more ergonomic grip.
The steel ends of each handle are pressed into a fishtail, inserted into the heads, and then molten iron is poured into the vacant space around the tails. When it cools, this creates a very secure dumbbell that doesn't not loosen from use over time like cheaper dumbbells.