No 12 Yellow colour filter to fit 1.25" filter threads (74% transmission). Enhances red and orange features on Jupiter and Saturn and blocks blue and green. It lightens the red and orange features on Mars and also enhances the distinction of blue clouds in the Martian atmosphere. Also useful to boost contrast in Lunar observing with scopes of 5" aperture and above. The filter is made of top quality optical glass and is mounted in a black anodised aluminium holder and is supplied in plastic storage case.