Explore Scientific T2 Ring - Canon DSLR 1.5MM Light-Path Silver M42x0.75. Regular T2-Rings needs a light-path of about 11-12mm and if you have a close backfocus situation these certain millimeters are making the difference to reach the focus. Specifications for Explore Scientific T2 Ring - Canon DSLR 1.5MM Light-Path: Manufacturer: Explore Scientific Color: Silver Features of Explore Scientific T2 Ring - Canon DSLR 1.5MM Light-Path Special T2-Ring Canon - M42x0.75mm thread Extreme short T2 ring design with 1.5mm height Recommended for close backfocus setups Straight use with Canon DSLR Made from stainless-steel Package Contents: Explore Scientific T2 Ring - Canon DSLR 1.5MM Light-Path Explore Scientific 510369: T2 Ring - Canon DSLR 1.5MM Light-Path Silver M42x0.75