Holiday Break: Orders will be processed through the new year. Shipping will resume January 2nd due to annual inventory maintenance. . . . . . . . . Happy Holidays!
The 121-136mm ring attaches to the font of the Cooke 25-250mm MK II via three set screws. It increases the lens form OD to a common 136mm size for clamp on accessories. Ring sits on OD of lens front housing so vignetting should not happen.