These measure 5mm thick and are 12x6mm. Vintage raw brass connectors. These have a patina with age. New old stock.
People often mistakenly think brass is one specific color, but since it is a mix of metals, mostly tin and copper, but often with other metals added, it has many variations. Some brass has a larger quantity of tin and is called "green brass", other brass has more copper and is called "red brass", something in between will resemble gold.
The color of brass also changes with time if it is exposed to air, getting an aged patina.
Everybody has an opinion as to what color brass is. Brass has many different hues. If you are looking for an exact match for something, please buy in a bead shop in person. I try to get my photos as close as possible, but monitors vary. I will not take responsibility for your opinion about brass. These pieces were originally made to be plated once the piece is finished. They will vary and I will not accept the blame if this is off from what you think brass should be.