This is a Parker 51 Signet Aerometric Demi pen and pencil set in 1/10 14 karat gold-filled cap and barrel c1949. The first Aerometric models are date coded 1948, though the launch was in 1949. The new filler unit that replaced the Vacumatic system is a clear "pli-glass" ink sac squeeze fill unit with a breather tube. The Signet was among three all metal Aerometric 51s introduced in 1949, along with the solid gold Presidential and the stainless steel Flighter. The engraving on the cap and barrel is three lines and a space. There is also a cartouche on the barrel for personalization. The Aerometric 51 was the top Parker pen until the introduction of the 61 in 1956. The Demi 51 is about 5 inches long and the caps are not interchangable with the longer standard size 51.