The 1916 Proof Lincoln cent is the lowest mintage coin in the Matte Proof Lincoln cent series.
Red: The 1916 Proof Lincoln is also the most difficult coin to find with complete Red surfaces for the Matte Proof Lincoln cent series. It is even tougher to find that the 1909 V.D.B. Proof in Red. Several of the 1916 Proof Lincoln cents in Red also tend to come with some spotting, or discoloration, possibly due to improper storage right after after the coins were struck.
PR66 Red or Higher: The 1916 Proof Lincoln cent is also the second scarcest in high grades with the Red color designation, with the 1911 Proof being the scarcest in PR 66 Red or higher. PCGS has only graded 3 different 1916 Proof Lincoln cents in PR66 Red with none higher. (Compare this to the population of the key coin to the series, the 1909 V.D.B. Proof, where PCGS has graded 7 in PR 66 Red and 2 higher in PR67 Red).