Not loose or tight / Cap design

Neither loose nor tight is a cap design, which on the cap and bottleneck part makes a skillfully handle with the bumps. On both sides of the cap, it increases the curvature bumps to facilitate unscrewed the cap. When the cap raised as portion and bottlenecks bumps are partial alignment, it means the cap is neither loose nor tight, just at a good location. The design is a good solution to solve the problem that screw a cap neither loose nor tight in everyday life, and not easy to unscrew cap.