Microloop, Euroloc, Microbead or Cold Fusion as they are called, are generally made from Aluminum. Some of them are lined with silicone to protect the human hair, they loop into small sections of the hair and clamped into place with the extensions attached. They usually last for 2-3 months. As the hair grows it is highly recommended for the client to go back into the salon - usually after 6-8 weeks to have the loops opened and slid back up closer to the scalp.
They are generally safe taken care of well. The funny down side that some clients have mentioned is that the beads sometimes causes some embarrassing moments when one has to go past security at the airport and the alarm sounds. But it is usually cleared when you own up to wearing these extensions which they can verify and send you on your way. Ha ha. You still look good, so no big deal right?