Ateco Tube Tip  Number 4B / 864 Large Open Star :

Tip #4B (or #864) is a Large Open Star piping tip, known for its finely cut teeth that create detailed, ridged icing patterns like shells, rosettes, and swirls, perfect for quickly decorating cupcakes, cookies, or filling deviled eggs, and is a standard tool for bakers, often made by brands like Wilton or Ateco.