The Sauterelle à lune perpétuelle is the most precise phase of the moon indication ever built in a wristwatch. It made it into the Guinness Book of Records. It is also the most precise phase of the moon by some margin: Approximately 2.045 million years.
The runner-up, by the way, is Andreas Strehler’s predecessor Sauterelle à lune perpétuelle with its precision of 14’189 years. Technically, the Sauterelle à Lune perpétuelle 2M is based on the Sauterellewhich Andreas Strehler presented last year. Like the Sauterelle, the 2M has Andreas Strehler’s unique remontoir d’égalité. This provides a constant supply of energy to the escapement.