This application relates to flush tank mechanism for a toilet bowl. The mechanism has a number of parts which are interconnected with each other. Such parts include, among others, an inlet valve, an elongated lever coupled to the input valve and having a channel throughout its length for feeding water from said valve along said channel to the tank via a float supported by the lever, and a hush tube coupled to said valve and providing a second path for feeding water into the tank. The mechanism also includes coupling means for quickly connecting parts, such as the lever and the input valve, to each other, or for disconnecting such parts from each other. Such coupling mechanism includes a rod which may be inserted into the apertures of two parts which are to be coupled to each other and having a head at one end, and a longitudinal bar of pliable plastic material mounted so as to be perpendicular to the rod and to overhang the head of the rod, whereby the coupled parts may be uncoupled by deflecting the bar so that the rod may be slid out of the apertures.