Brass drain plugs typically require the following characteristics:

Material: Brass is commonly used because it is durable, corrosion resistant and has good sealing properties.

Dimensions: The plug should fit snugly over the drain opening on your boat.

Sealing: They should have a good seal to prevent water from entering the boat through the scuppers.

Ease of installation and removal: Plugs should be easy to install and remove as needed for proper drainage from the boat.

Durability: Brass drain plugs are resistant to water and air corrosion.

It is to be noted that the regulations regarding brass scupper plugs may vary by country and vessel type and it should be ensured that the relevant regulations are followed.