FASTENER

The present invention provides for a fastener for securing to at least a first panel having a collar defining an opening formed therein, the fastener comprising: a fastening portion adapted to be inserted in a first direction through the opening of the collar and then moved in a second direction into an engaged positioned to secure the fastener to the first panel, the second direction being opposite to the first direction; and a body having a circumferential gasket secured thereto such that the gasket is arranged to sealingly engage with an inner surface of the collar when the fastener is inserted into the collar; wherein the gasket is configured to engage the inner surface of the collar to provide a first level of resistance when moving in the first direction and a second level of resistance when moving in the second direction, the first level of resistance being lower than the second level of resistance.