The ISO NOrm describes the size and form of the pallet fork carriers according to the lifting capacity.
The ISO 2328 informs about which size has to be used for the lifitng capacity of the loader.
ISO FEM II: 1000-2500kg lifting capacity
ISO FEM III: 2501-4999kg lifting capacity
ISO FEM IV: 5000-10000kg lifting capacity
Besides the ISO Norm there are also pallet fork carrier according DIN Norm. Bressel und Lade only uses one DIN carrier.
Other manufacturer (example: Kramer, Schäffer) are using other sizes. Please request.