Jaeger Lecoultre 839 / IWC 1852 third wheel / part 210

Jaeger Lecoultre 839 third wheel , not for JLC 838

Also for IWC 1852 

Part 210 , diameter 5.06mm

Roue de moyenne pour Lecoultre 839 (ne convient pas au calibre 838)

Pre-owned / pre-used, dismounted from JLC 839