Regular dumbbells are great for strength training as long as you have the right fitness plan. These O2 Magnetic Dumbbells take it a step further. They are portable and have embedded electromagnets. The strength of these electromagnets can be set easily. You don’t have to carry different dumbbells for more intense workouts. These dumbbells weigh from 3kg to 24kg. The idea is conceived by Suhyun Yoo, Hongseok Kim and Juhyeon Lee. This looks interesting but we are not sure how practical it is.