Features machining and flange distance calibration for accurate focus, eliminating vignetting and soft edged Made with ABS for wear resistance, ensuring long term stability without loosening Seamlessly adapts M42 mount lenses to cameras, imaging at low cost Large 45mm inner diameter and matte interior dark corners and light, clean edged to edged image on GFX sensors Simple setup with secure Double locking mechanism; M42 lenses for flexible control