2 1/2 oz gin (I like Bombay Sapphire in this one.) (7.5 cl, 5/8 gills)
3/4 oz grapefruit juice (2 cl, 3/16 gills)
1/2 oz sweet vermouth (1.5 cl, 1/8 gills)
Shake in an iced cocktail shaker, and strain into a cocktail glass.
Serve in a cocktail glass (4.5 oz)
