Double & Double Rollers with Zinc Rollers:
This configuration may refer to a setup where both the upper and lower rollers are doubled, and all rollers feature zinc construction. The use of zinc rollers could offer benefits such as corrosion resistance and durability. This setup might be chosen for applications where a higher load capacity or increased stability is required.
Double & Single Rollers with Zinc Rollers:
In this arrangement, one side (either upper or lower) has double rollers, while the other side has a single roller, and all rollers feature zinc construction. The zinc material provides corrosion resistance and may contribute to the overall durability of the rollers.