Q: Which proxy formats can I get?
A: We offer proxies with user and pass, by default they are sent in the ip:port:user:pass but you can rewrite that in any format which is accepted by your program (ex user:pass@ip:port) via buyproxies.org/panel/format.php
There isn’t any difference between the formats, the sites will only see the proxies IP. The format is just for the authentification on the proxy so you can be only which will use it. Without any type of authentication everybody will could use.
If you use IP auth from http://buyproxies.org/panel/ips.php there is no need for user and pass on the proxies, so you can use them in IP:port format.