Gerber mp 600 blade type.

[Wozer1]

Hi. Does anyone know why in some pictures of the mp600 for sale they have a thin fine edge blade and others the thicker type blade.? Some serrated some not. I am looking to purchase 2 for my collection 1 black and 1 stainless. I have just purchased 2 mp400s from the US they have the thinner longer looking half serrated blade but are in the older type grey box.Gerber UK don't seem to have the thinner fine edge blades. Are they still available or only on older US models. I think. Any expert advise would be helpfull