For a short time, believed to be in 1907, Griswold produced skillets with "artistic" lettering. Prior to the fourth series, the lettering had basically been of block nature. In addition to the artistic lettering, the fourth series was made with both the outside heat ring and the new inset heat ring.  All of the ERIE pattern numbers were 3-digit numbers, except for the No. 5 in the artistic lettered Fourth Series. For some reason that is not understood, a four-digit number, 3348, was used on a portion of the production instead of the usual 724.  Another unusual occurrence with the Artistic Fourth Series skillets is that the abbreviation “No.” was used before the skillet number. This abbreviation was not used on any other series.  Only the rare #5 and the #9 skillets are known to exist.