Baader 2-Inch SC Deluxe Visual Back With 2-Inch Filter Holder 2958144 (UK)
In the Version SC-Deluxe eyepiececlamp with 2" filter holder(#2958144) the third part is a M48 filter holder. Protects the interior of your SC-tube from dust by the incorporation of any Baader 2 "filter (UV / IR cut filter).