Pentax designed the 9x42 S-Series SD WP Binoculars for a lifetime of rugged outdoor use in all weather and lighting conditions. The 42mm objectives are fully multicoated to reduce reflection and maximize light transmission through the entire optical path. Their roof prisms are phase-corrected to correct for chromatic aberrations ensuring bright and clear high-contrast images with true color rendition even in low-light. Their 9x magnification brings subjects a bit closer over the more common 8x, but reduces the visible shake often associated with higher magnifications.

Complementing the optical performance are construction details made for the trail. The optical tubes are nitrogen-filled and O-ring sealed for fogproof performance and to make them submersible to as much as 3.3'. An open bridge design cuts weight without sacrificing strength to reduce user fatigue during long glassing sessions. The binoculars sport a generous 18mm eye relief and their twist-up eyecups ensure comfortable viewing with or without eye wear. Protective coatings on the exterior lens surfaces repel water, dirt, and oil to keep them clean for unobstructed viewing.