Special parts allowing to prevent the access doors from being opened: two metal knobs with holes (11 mm Ø), one locking bracket and two washers. These parts can be installed on practically any METU access door (some tools are required). Secured with two standard padlocks (not included).
Made by METU in Germany
CAUTION This solution is not recommended, as the retaining cable can easily be teared off with a large screwdriver or a metal bar used as lever