The Bulgarian Helsinki Committee explains in a short animated video who are prisoners in a situation of vulnerabilities, what international standards say about them, and why it is important for National Preventive Mechanisms to place special attention on this issue. This video was produced as part of the EU funded Project "Improving judicial cooperation across the EU through harmonised detention standards - The role of National Preventive Mechanisms" by the Ludwig Boltzmann Institute of Fundamental Human Rights, the Associazione Antigone, the Bulgarian Helsinki Committee, the Hungarian Helsinki Committee.