A reagent container assembly adapted for being installed in a cavity of an
analyzer. The reagent container assembly comprises a housing having an
upper opening and defining at least one circular array of chambers, each
chamber being adapted for receiving a reagent container, a cover for
closing the upper opening of the housing, and a locking mechanism
arranged within the housing. The locking mechanism is adapted for locking
the cover and for preventing rotation thereof. The locking mechanism is
further adapted for locking the housing and thereby preventing rotation
thereof when the reagent container assembly is removed from its position
in the analyzer. The locking mechanism is further adapted for cooperating
with a pin arranged at the bottom of the cavity of the analyzer when the
reagent container assembly is installed in the analyzer, the housing
being unlocked by the cooperation and thereby allowed to be rotated
within the cavity of the analyzer.