Flybird Adjustable Dumbbell The Flybird Adjustable Dumbbell ($150) is like having five dumbbells in one, with settings ranging from five to 25 pounds. It has nearly 500 five-star Amazon reviews, with one reviewer calling the product "easy to use" and "worth the price." Image Source: amazon.com Flybird Adjustable Dumbbell $150 from amazon.com Buy Now