12.5" (317mm) Helios Solar Glass Filter. Fits Optical Tube Diameter 12 1/8" (308mm) to 12 3/8" (314mm)

I bought Helios Solar Glass Filter 12.5" (317mm). Fits Optical Tube Diameter 12 1/8" (308mm) to 12 3/8" (314mm). SF1250, excelent product, I use with my CGEM 11" Celestron, fit excelente, I can take nice pictures, I recomend.