Anonymous Proxy server does not send HTTP_X_FORWARDED_FOR variable to host, this improves privacy since your IP address cannot be logged.
Elite proxy (high anonymity) does not send HTTP_X_FORWARDED_FOR, HTTP_VIA and HTTP_PROXY_CONNECTION variables. Host doesn't even know you are using proxy server and of course it doesn't know your IP address.
212.117.166.26:3128
213.239.219.245:8080
218.30.114.202:80
220.128.122.187:80
221.116.142.90:80