This will hold 1.25" Filters for PVS-14 & Envis objective lenses.
The adapter should friction fit into the front with the splines perfectly matched.
Use the customizer to adjust any fit issues or change any of the dimensions.
UPDATE: 1/24/19. The design is updated with threads so 1.25" filters can thread into the adapter. I printed at 0.120mm layer height and the printed threads work great. They may need some tweaking to work well with your printer.