WPC Fence Board Flat 140 x 20 mm (2.5 kg/m) is the steadier board in the range. Same 140 x 20 size, but at 2.5 kg per meter it carries 0.4 kg more than the lightweight hollow board - and that extra material all goes into the board itself, with a higher fill rate and thicker walls. The 140 mm face means fewer joints and full screening, and the 20 mm thickness keeps the board stiff. Outdoor performance is unchanged: it takes in no water, so it will not rot, split, host insects or grow mould; UV-stabilised so the colour will not bleach; no paint and no wax, ever. For a fence that is steadier, stands up to wind and is easier to keep clean, choose the flat board. For the lightest board and the fastest install, choose the 2.1 kg/m. 140 x 20 mm flat fence board, 2.5 kg/m - more material behind it, stands up to wind, and a flat face that is easy to keep clean.