The Nixon 48-20 watch is a smaller version of the 51-30 but has similar features. Because of the smaller size of 48-20 it is lighter and fits almost all wrists. Upon reviewing the 48-20 you'll notice subtle differences between the 48-20 and the 51-30 including the sub-dials have been changed to provide more spacing. All 48-20 Nixon watches have a two year warranty and are waterproof to 300 meters so they perfect for surfing, snorkeling, spear fishing, swimming, full submersion, showers, baths, hot tubs, and any other water you can throw on it. Just be sure that the crowns are fully closed and locked before submerging.