Also like the 10x42s, the 12x50s have an easy-to-use central focus knob that allows you to quickly adjust your range of focus. This comes in handy when watching fast objects or animals. The two pairs of binoculars both have an ergonomic design, so that you will not get hurt from long watches. In fact, the two pairs of binoculars share most of their features in common, the difference being in objective diameter (50 as opposed to 42), magnification (12x as opposed to 10x) and the real angular field of view (5 degrees as opposed to 6), which makes a difference in the Field of View from 1000 yds. (262 ft. as opposed to 314 ft.). Like the 10x42s, the Nikon Premier SE 12x50s are made from Eco-Glass, which means that they contain no lead or arsenic.