[en] The Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider at CERN will use Resistive Plate Chambers (RPCs) as a system for muon detection. RPCs will be also a relevant part of the dedicated muon trigger. The CMS barrel region will be equipped with 480 double gap RPCs operated in avalanche mode using a Freon based gas mixture. A great effort is being done to customize a detector able to satisfy the stringent requirements needed to operate in a hostile background environment during normal operation. Excellent muon efficiency, high rate capability, good time resolution, low cluster size and low neutron and gamma sensitivity will characterise the system. Such features have been carefully evaluated during the detector design and measured during the following R and D program. As the mass production started an intensive commitment period for monitoring the quality of the RPCs followed and involved researchers from Bari, Napoli, Pavia and Sofia Institutes. Production and assembling of the detectors was managed in Bari, Napoli, Sofia and at General Tecnica factory; cosmic rays tests in Pavia, Bari and Sofia assured the chambers final quality certification. Further tests at the CERN ISR site completed the process before the final installation on the experimental site. The detector performance will be analyzed in detail; the quality control procedures of the main RPC components will be reviewed as well as the cosmic test results for the mass production accomplished so far. Problems encountered and the adopted strategies for their solutions will be also discussed