Based on this product's specifications, here are some alternatives and similar models
Suki Hexagon Cap Nut M4 A2 Stainless Steel 10 Pieces
Summary description:
Suki M4 hexagon cap nuts made of A2 stainless steel, supplied in a pack of 10. These fasteners provide a clean, finished look while protecting exposed bolt threads from damage and corrosion. Ideal for various assembly projects requiring durable, weather-resistant hardware in indoor and outdoor applications.