This invention pertains fasteners which are characterized by adaptability of use with substrates, such as steel panels for example, of various thicknesses. This is achieved predominately by providing the fastener with legs having an origin section in the vicinity of the head of the fastener. Expansion promoters and/or anti-sliding elements improve considerably the separation resistance of objects connected with the fasteners of the present invention. Assemblies and vehicles comprising the spring fasteners of this invention, connecting two objects, one of the objects comprising a slot in which the fastener is inserted, and the other a hole, are also included within the scope of the instant invention. Provision of an elastic body in the vicinity of the bottom section of the fasteners provides water and gas proof properties, and further assist in the elimination of squeaking noises.