Abstract: A refill device for a receptacle provided with a threaded neck including a receptacle, designed to contain a product to be transferred into the receptacle, a cooperation structure designed to form a connection between the first and a second receptacle, a closing structure for closing off the receptacle, a transferring structure for transferring the product contained in the receptacle to the receptacle. The cooperation structure includes a threaded base capable of cooperating with the neck, the closing structure comprises a wall closing off the base, designed to be broken off by an axial force, the transfer structure includes an axial packing designed to be placed above the wall, such that during the said screwing of the neck, the neck pushes the axial packing into contact with the wall, so as to break the wall and enable the liquid to flow by gravity.