Audemars Piguet have released forty of the Openworked Extra Thin Royal Oak Limited Edition sports watches to celebrate the fortieth anniversary of their Royal Oak collection. It shares the same thirty nine milimeter diameter as the first one launched in 1972. The new platinum folding clasp features a double safety fastening system and a platinum case with glareproof sapphire crystals. Thirty six jewels and twenty two karat gold make up the automatic calibre 5122 movement.