P40 Phase-Corrected Roof Prisms HighLux Fully Multi-Coated Optics. HDC and AquaDura Optical Coatings Fogproof and Submersible to 16.5 Feet. Closed-bridge/dual-hinge configuration provides a sturdy platform Wide 34-74mm interpupillary distance range. 3.5 right-eye dioptric correction Twist-up rubber eyecups for comfortable use. 15mm eye relief makes long-duration glassing sessions more comfortable