Mixers are gatherings for singles without a particular ice breaking method. No bell, no scorecards, no keys. Just a group of singles who want to freely socialize without rules and in their own time.
Each participant has to break the ice on their own and approach or let be approached by others. Sharing contact information is your responsibility.
One of the advantages is that you decide who to talk to and for how long when compared wirh speed dating where you have to talk to everyone for a specific time.
Sometimes the venue is secret and will only be revealed to those you sign up.
Usually food or drinks are not included with the entrance tickets.