A glass tumbler featuring a design applied to the interior surface. The angle and placement of the pattern are precisely calculated to allow the tumblers to be stacked neatly. When filled with water, the interior pattern visually disappears, creating a subtle and surprising effect. The exterior is intentionally left free of decoration, ensuring a comfortable grip and ease of handling. Its gently curved form is designed to fit naturally in the hand, balancing visual refinement with everyday usability