An adjustable socket system includes first and second shell components and first and second longitudinal supports connected to a base. The socket system is movable between an open configuration to loosen the fit of the socket system, and a closed configuration to secure the fit of the socket system on residual limb received therein. A tightening system includes a tensioning unit having a handle defining a moment arm rotatable about a rotation axis, and a tensioning element operatively coupled to the handle via a movable connection point located and protected between the first shell component and the first support and to the shell components via a control point. Rotation of the handle displaces the movable connection point and the tensioning element relative to the control point to move the socket system to the closed configuration.