To provide fittings which make a person hardly stumble by making his/her toe hardly caught in the rail groove of a lower guide rail, which facilitate the cleaning of the inside of the rail groove, which prevent the deformation of the lower guide rail when he/she tramps on the lower guide rail, and which prevent the generation of a metallic squeak noise.

The lower guide rail 3 for guiding a lower portion of a panel body 1 comprises an outer metallic rail 10, a nonmetallic rail supporting member 20 which is provided in the rail groove 10a of the outer rail 10, and an inner metallic rail 30 which is supported by the rail supporting member 20. The rail groove 10a of the outer rail 10 comprises a pair of breadthways vertical surfaces and a bottom surface. The inner rail 30 and the rail supporting member 20 are mutually fitted together, so that the displacement of the inner rail 30 in a breadthways direction can be restrained. The rail supporting member 20 is brought into contact with the bottom surface of the rail groove 10a of the outer rail 10. A gap is made between each of both breadthways side ends of the inner rail 30 and each of the vertical surfaces of the rail groove 10a of the outer rail 10.