ok do you mean saddle or gaucho or gaucho saddle? gaucho saddle is in one size, gauchos can be either large, medium or mini ( with longer or shorter strap) , or totes - zipped ( 2 sizes) or with magnetic clasp.
enclosed pics of all, for exact sizes i recommend visiting www.dior.com shop online where all the dimensions of all models are given.
here is mini with shorter and longer strap, tote with magnetic clasp, a medium gaucho and a double ( large) one.
tote 36 x 24 x 7 cm , same for medium gaucho, though shape is a bit different, 36 x 25 x 14,5 cm for the zipped tote ( the smaller size i think ),
25 x 17 x 8 cm mini gaucho, 36 x 25 x 14 cm large gaucho, 30 x 23 x 8 cm gaucho saddle.