A double-glazing unit (1) comprises a frame (2), two panes (3a, 3b), which are at least partially transparent and fixed to the frame (2) and screening means (5) located between the panes. The screening means (5) comprise at least two sets (6a and 6b) of slats (7) in mutually facing positions, at a predetermined distance from each other to define visibility zones (10). The slats (7) are configured to slide along a sliding direction ("Z"). Thus, the screening means (5) are adapted to be switched from an observation configuration in which the slats (7) of each set (6a) face the slats (7) of the other set (6b) to a privacy configuration in which the slats (7) of each set (6a) face the visibility zones (10) of the other set (6b) to block the passage of light.