.decimal proton apertures are made from high grade domestic brass. Whether your needs are patient specific or prepped blanks for in-house machining. .decimal patient specific apertures can be beam divergent corrected if required. Our patented shell and core design cuts down brass consumption by utilizing reusable stainless steel shells and smaller brass inserts suitable for smaller openings. Adapter rings for range compensators allow for the use of smaller range comps where applicable, further reducing costs.