When placing your spares order, please be sure to provide full details of your machine. For example, just saying "MV 125" or "MV 350" doesn't really help. We need to know exact model, eg. 350B Sport Electronica - this, for instance, tells us that it's a round case engine in sport trim and with 12v electrics, all of which helps us identify the correct parts.
Part numbers are essential for all later models but for the early singles we require page and item number instead.
Engine and frame numbers are a great help also.
If at all possible, photos of the bike and/or individual part(s), are a great help, eg exhaust identification can be a nightmare on the singles.
Contact details, especially email, or the forum provide a quick way of sorting out any queries.