Abstract: A connector system (20) for interconnection of optical fiber ferrule connectors in optical wiring panels includes an array of buildout blocks (70,70) which are mounted in a panel (60). Each buildout block includes a tubular portion (76) having a keyway and provisions for receiving a buildout (100,150) which upon suitable alignment and rotation relative to the buildout block is caused to be secured to the buildout block. The buildout (100) which is adapted to receive an ST.RTM. connector includes a first tubular portion (103) in which is disposed a sleeve (107) for receiving a plug (40) of a plug assembly (22) of the connector system in one end thereof which has been inserted into the tubular portion of the buildout block with a key (43) thereof received in the keyway (78) of the tubular portion of the buildout block. Also, the sleeve is capable of having an attenuator element (140) mounted therein.