Guerlain L'essentiel Retractable Foundation Brush The Retractable foundation brush by Mathieu Lehanneur has an ergonomic design for an intuitive application technique that naturally enhances the foundation make-up result. This pleasant ritual is gentle on the skin.Foundation is easy to apply with precision, even to difficult areas such as the eye contour. The result is even without any streaks or demarcation lines for a natural make-up finish with a “bare-skin” effect.Its retractable sleeve protects the soft, synthetic fibres. The brush remains clean and fresh use after use. It is easy to clean and does not lose its fibres.