The cushion-shaped 40 mm case elegantly surrounds the dial, which is thoroughly vintage and true to the original model. 

The Longines Heritage 1973 houses calibre L688, a column-wheel chronograph movement developed and produced by ETA exclusively for Longines. 
 

The Longines Heritage 1973, ref. L2.791.4.52

The Longines Heritage 1973, ref. L2.791.4.52 © Longines

The black dial of the Longines Heritage 1973 boasts a play of contrasts. Two silvered counters were included at 3 and 9 o'clock. The applied hour symbols are decorated with a fine black line and a dot of Super-LumiNova®. These are interposed and balanced out by a minute-circle, also of fine black lines. A blue tachometric scale surrounds the dial, adding a subtle touch of colour to the whole.