The three ingredients of a Racquet Club are Gin, Dry Vermouth and Orange Bitters. Interestingly enough, you can make a Leaning Tower, Delmonico or an Astorio Bianco using those exact ingredients and nothing else. It is all in the proportions.

This one has 3 ounces of gin, 1 ounce of dry vermouth and 4 dashes of orange bitters.