MONTBLANC BLANC BLUE 3.0 BUCKLE BELT in Mont Blanc Blue 3.0 Buckle Belt. The Montblanc Reversible Belt with M Extrem 3.0 Buckle offers the best of both worlds. With black leather textured on one side and smooth on the other, it's a versatile mix of sportiness and elegance. The bold "M" buckle embodies Montblanc's timeless design.