On Apr 15, 14:24, David Woyciesjes wrote: DEC (and Sun, etc) used something like that but with a real nut welded (?) onto the clip, like the diagrams at the top of http://www.tt-ec.com/showcase/nutbolt/utypenrcat.html I've always known the ones DEC used simply as Tinnerman nuts. The other type used by DEC is like a strip of spring steel wrapped round the nut and then formed into a springy clip that clips round the rails (sorry, can't find a picture). The correct size for rack screws is 10-32 UNF, rather smaller than any of the ones on the PalNut page. The picture of a retainer nut (which happens to be made by Tinnerman in this case, but isn't what I'd call a "Tinnerman nut") at the top of that page is of what everyone over here calls a "caged nut". They're used on european racks, which have square holes not round ones; the normal size takes an M6 screw (DEC screwss are 10-32 UNF, which is very similar to M5). -- Pete Peter Turnbull Network Manager University of York