The present example of the 2499 has its case made in yellow gold. It was produced in 1980 and bears the retailers (Beyer) signature on the dial. The fourth generation of 2499 is also known as 2499/100There are generally four versions of the 2499 to be distinguished:- first series: square chronograph buttons, applied Arabic numerals andtachymeter scale (1951-1955)- second series: round chronograph buttons, either applied baton or appliedArabic numerals and tachymeter scale (1955-1960)- third series: round chronograph buttons, applied baton numerals and outerseconds divisions in 5′ increments (1960-1978)-fourth series: round chronograph buttons, applied baton numerals, outerseconds divisions and sapphire crystal, such as the watch pictured (1978-1985)
