There are more than 135,000 Committees for the Defence of the Revolution (CDRs) in Cuba. There main purpose is to ensure that nothing - or no one - puts the achievements of the Revolution at risk. "With the help of the CDRs, we know who is who and who does what", explains Ruben Perez, Deputy Manager of the CDRs. Committees can hand out warnings to citizens deemed acting inappropriately. Those who fail to change their behaviour are then imprisoned for up to four years. People can also be imprisoned for moving from one town to another without a visa. When released, political prisoners are constantly monitored. "I am like a prisoner in my own neighbourhood", complains one former prisoner. "I'm afraid to visit anyone because I don't like to complicate anyone's life by my presence". Few people expect life to change soon. "I don't have any illusions about Fidel Castro's death leading to major democratic changes", states one man. "The generation that created this system will still be in power".