The celestron nature dx 8x42 binoculars are celestrons new nature series and is the perfect companion for the outdoor explorer these feature packed binoculars offer multi coated optics bak 4 prisms and a fully waterproof exterior that is purged of air and filled with dry nitrogen gas to ensure a clear fog free viewing experience the bak 4 prisms with phase coating increases contrast and resolution for sharper and more detailed images the multi coated optics provides maximum light transmiss