These smaller solid brass binoculars can be used as opera or field glasses. Focusing is accomplished with a single center adjustment. Since these binoculars do not have prisms, they have a smaller field of view as compared to modern binoculars. The Small Brass Binoculars measure -Polished solid brass and precision ground glass lenses -Convenient center focus knob -Hand Made Binocular -Made with Brass -Pirate Nautical Maritime Collection -Toys & Games