LB is short for the British and American unit of weight "pound". One pound is equal to 0.45359 kg. So dumbbell 4LB is a dumbbell weighing about 3.6 Jin.

Dumbbell is a simple instrument to strengthen muscle strength training. Its main material is cast iron, which is covered with a layer of rubber.

Pound (English: Pound) is a British unit of mass used in Britain and the United States, abbreviated as lb. After years of evolution in history, the quality system in Britain has also produced many different definitions of pounds, such as troy pound, tower pound, commercial pound, London pound, metric pound, international pound and so on. The most commonly used definition is international weight (international pound).

One pound equals 453.592 37 grams, 1958 was recognized by the United States and other Commonwealth member countries; Converted back, one kilogram is equal to 2.2046 2262 pounds, and one pound is equal to 0.4535 9237 kilograms. Starting from 1963, Britain changed the definition of international pound according to the provisions of the Weights and Measures Law.