This 2" universal field flattener was designed for f/5 to f/7 refractors and is a field flattener of choice for the Founder Optics FOT86 when doing astrophotography.  Like most field flatteners, it requires 55 mm of back focus.

The FLAT1.0 is compatible with both M42 and M48 threads, comes with protective caps for both ends, and has a strong, beautiful glossy anodized finish.