Pentax D FA 24-70mm F2.8ED SDM WR Lens (Black) SDM (Supersonic Direct-drive Motor) - Shoot discreetly with in-lens, Auto Focus motor operation for quick, smooth & quiet performance. HD (High Definition) - Treated with state-of-the-art HD technology; a high grade, multi-layer coating, allowing the user to capture crisp, high-contrast images free of flare and ghosting, even under demanding lighting conditions. ED (Extra-low Dispersion) glass lens elements deliver clear, high resolution imagery with outstanding edge-to-edge sharpness throughout the entire zoom range. WR (Weather Resistant) - Designed with 5 special seals to prevent intrusion of water.