Equipped with a large aperture and a broad zoom range, the Celestron 15-35x70 SkyMaster Zoom Binoculars are an ideal choice for long-duration astronomical or long-distance terrestrial use. The large objectives ensure volumes of light are gathered to see better than smaller-aperture models, and the easy zoom lever allows you set the binoculars on low-power to easily find your subject, then zoom in to detailed, close observations. These binoculars are engineered with an exceptionally long eye relief to make them comfortable to look through for extended periods of time, while limiting eye strain. Because of the size and weight of the SkyMaster binoculars, Celestron includes a tripod adapter to provide a hands-free option and relieve arm-strain, reduce fatigue, and limit vibrations.