Ross Xpres London 2 Inch F1.9 Rare prestige English lens manufactured around 1939. Construction of Double Gauss type (1-2-2-1) designed 1938 (i.e. near - symmetrical, each half comprising of a single element and a cemented doublet). The rear component is made up of three glasses instead of two, providing still more possibilities for correction of aberrations. ㊣㊣㊣㊣㊣