Brake fluid reservoir connection rubber. For the connection from the glass container to the master brake cylinder

Dimension: Diameter above: about 20-21mm. Diameter down: about 12mm. Inside diameter down: 8.0mm. This system of the securement was used with many französichen car. E.G. Citroen 11CV + 15CV, Citroen HY, Citroen Ami. Peugeot + Renault.