150mm Graphic kowa lens

Hello everyone. I purchased a 150 mm F9 grapic kowa lens on e-bay. There is a slot in front of the aperture ring with a double spacer resembling a negative holder of an enlarger. Does anyone knows if removing this spacer may affect the performance of the lens? Any help will be appreciated. Thanks. Pierre

No. It's for cutting gel filters and inserting them between the elements. Also could be used for waterhouse stops. Mostly they get removed and lost. Nice lens.