The Elgin 998 is a manual wind watch movement with a sub-second function. It was produced by FHF in their Fontainemelon factory. The movement is part of a series of calibres, including the Gruen 100, 101, 620 through 623, 626, and 627, that are based on the FHF Robert 8.75''' calibre downsized to 8'''. However, specific differences between these calibres are not known. The Elgin 998 movement was used from 1918 onwards.