The 3003 aluminum expanded sheet has a flat, unpolished (mill) surface. The 3003 aluminum alloy provides good strength and corrosion resistance, and is lighter weight than steel, copper, and brass. The flat sheet has been rolled for a smooth, level surface.

Expanded metal sheets are created by slitting and cold-forming metal as it expands in a press. This process creates diamond-shaped openings that are nominally measured the long way of the diamond (LWD) and the short way of the diamond (SWD). Raised, or standard, expanded sheets offer a skid-resistant surface and a high strength-to-weight ratio. Flat expanded sheets have been rolled for a smooth, level surface. Expanded metal sheets are measured by the percentage of open area, which is the ratio of open space to total space in a given area. A sheet with a larger percentage of open area contains less material than one with a smaller percentage.