A kit for transportable containers, for the coupling of an external accessory, such as a tripod or the like, to a transportable container; the container includes first and second half-shells which are mutually articulated. The kit includes at least: a first member which has a head and a threaded pivot, which extends from the head and which can be inserted into a hole which is provided along the first half-shell, a second member which has a female thread which can be engaged by screwing with the pivot, and an annular gasket, which can be fitted over the pivot and can be fastened between the head and the first half-shell.