Take a guess what these are for and why they are made of brass and copper? 

Any takers? 
https://nostrcheck.me/media/baeb862f3318390ec5af5c9db64ae5ddb2efc1a97db54c6550656bfa2dcc054b/ae8c92aea57455540e488a6e9f7b8cb06477662d8c6f66d803311694491367d5.webp