Optical power in Water: +23 dioptres
Aluminum body (6082) Hard anodized coated 40 microns
Two flat glass BK7 with anti scratch and anti-glare
5 elements, 3 groups
Compatible cameras: Optimized for sensor sizes 36 mm x 24 mm (135 mm full frame)
Magnification: x4.2 (Area Ratio x17.24) with 105mm F2.8 Macro Lens
Working Distance: 27mm - 36mm (from the front lens surface) 
Weight (air): 593g
Weight (water): 379g
Diameter: 71.8 mm
Length: 60.3mm
Depth rating: 60m