Fill half-way two cocktail glasses with ice. To each glass, add half of the tequila, lime juice, cranberry juice, grapefruit juice and simple syrup. Stir well to combine. Top with club soda then stir gently.
cubed ice, 4 oz tequila (Blanco or Reposado) , 1 oz fresh lime juice , 2 oz cranberry juice (unsweetened) , 2 oz grapefruit juice (freshly squeezed or store-bought) , 1 oz simple syrup (or more to taste) , Club soda, to top