This antique, The D.H. Hogg Co. Montreal No. 4 "Laurie" Rapid Rectilinear 8x10 266mm f/8 brass lens has a rear thread diameter of 54mm. It does not come with its mounting ring. There are a few scuffs, scratches, and oxidation on its exterior. Please see photos. There is separation around the outer perimeter of the front element grouping. Its aperture adjustment is smooth, and its glass is free of any fungus or haze.