An assembly for securing a flow meter against opening comprising: - a mounting ring, - a counting mechanism cover, - a shielding ring, whereby the mounting ring is adapted to mount on a flow meter body and comprises: - at least two security latches adapted for mounting the ring on the side of the flow meter body, and the counting mechanism cover is adapted to lock the mounting ring and the shielding ring and comprises: - at least two locking elements for locking its rotation relative to the mounting ring, while the shielding ring is adapted to cover the counting mechanism cover, characterized in that, the mounting ring further comprises: - at least two retaining latches adapted to support the shielding ring, - a pair of ribs adapted to protect against its spreading, and the counting mechanism cover further comprises: - locking splines preventing the retaining latches of the mounting ring from bending back, wherein the at least two locking elements are also for locking its rotation relative to the shield ring, and the shield ring is further adapted to cover the counting mechanism and comprises: - a pair of ribs reinforced with additional walls to prevent bending outwards and spreading of the mounting ring, - at least two notches adapted to latch the retaining latches of the mounting ring, - at least two latches adapted to face its walls with the walls of the mounting ring and block the rotation of the counting mechanism cover in cooperation with the locking elements of the counting mechanism cover. - a mounting ring, - a counting mechanism cover, - a shielding ring, whereby the mounting ring is adapted to mount on a flow meter body and comprises: - at least two security latches adapted for mounting the ring on the side of the flow meter body, and the counting mechanism cover is adapted to lock the mounting ring and the shielding ring and comprises: - at least two locking elements for locking its rotation relative to the mounting ring, while the shielding ring is adapted to cover the counting mechanism cover, characterized in that, the mounting ring further comprises: - at least two retaining latches adapted to support the shielding ring, - a pair of ribs adapted to protect against its spreading, and the counting mechanism cover further comprises: - locking splines preventing the retaining latches of the mounting ring from bending back, wherein the at least two locking elements are also for locking its rotation relative to the shield ring, and the shield ring is further adapted to cover the counting mechanism and comprises: - a pair of ribs reinforced with additional walls to prevent bending outwards and spreading of the mounting ring, - at least two notches adapted to latch the retaining latches of the mounting ring, - at least two latches adapted to face its walls with the walls of the mounting ring and block the rotation of the counting mechanism cover in cooperation with the locking elements of the counting mechanism cover. whereby the mounting ring is adapted to mount on a flow meter body and comprises: - at least two security latches adapted for mounting the ring on the side of the flow meter body, - at least two security latches adapted for mounting the ring on the side of the flow meter body, and the counting mechanism cover is adapted to lock the mounting ring and the shielding ring and comprises: - at least two locking elements for locking its rotation relative to the mounting ring, - at least two locking elements for locking its rotation relative to the mounting ring, while the shielding ring is adapted to cover the counting mechanism cover, characterized in that, the mounting ring further comprises: - at least two retaining latches adapted to support the shielding ring, - a pair of ribs adapted to protect against its spreading, and - at least two retaining latches adapted to support the shielding ring, - a pair of ribs adapted to protect against its spreading, and the counting mechanism cover further comprises: - locking splines preventing the retaining latches of the mounting ring from bending back, wherein the at least two locking elements are also for locking its rotation relative to the shield ring, and - locking splines preventing the retaining latches of the mounting ring from bending back, wherein the at least two locking elements are also for locking its rotation relative to the shield ring, and the shield ring is further adapted to cover the counting mechanism and comprises: - a pair of ribs reinforced with additional walls to prevent bending outwards and spreading of the mounting ring, - at least two notches adapted to latch the retaining latches of the mounting ring, - at least two latches adapted to face its walls with the walls of the mounting ring and block the rotation of the counting mechanism cover in cooperation with the locking elements of the counting mechanism cover. - a pair of ribs reinforced with additional walls to prevent bending outwards and spreading of the mounting ring, - at least two notches adapted to latch the retaining latches of the mounting ring, - at least two latches adapted to face its walls with the walls of the mounting ring and block the rotation of the counting mechanism cover in cooperation with the locking elements of the counting mechanism cover.