A retaining mechanism for a holster includes a body (18) mountable to or integral with a holster, and a hood unit (40) rotatably mounted to the body. The hood unit configured for rotation about a first axis between a retaining condition in which it overlies a service item in the holster to prevent its withdrawal and a retracted condition in which the service item can be withdrawn. A hand-operable lever assembly (60) is rotatably mounted to the body and configured for rotation about a second axis. The lever assembly is operably engageable with the hood unit whereby rotation of the lever assembly effects rotation of the hood unit to its retracted condition and vice versa. The lever assembly includes a first, deflectable, portion (70) and a separate second, depressible, portion (80). These first and second portions are respectively selectively deflectable and depressible against respective first and second restoring bias forces to disengage the lever assembly from a lock formation (128) configured to lock the lever assembly against rotation and thereby the hood unit against rotation to its retracted condition. Also disclosed is a blocking element (160) moveable from a position in which it impedes or obstructs the lever assembly. In another aspect, a portion (150) of the lever assembly is releasable restrained between a portion (128) of the hood unit and a portion (110) of the body.