A 140 × 30 mm solid straight-grain WPC decking board, co-extruded in one piece from wood-plastic composite, weighing a substantial 4.76 kg per metre (core density around 1.13 g/cm³, standard formulation) — the deepest-section, highest-stiffness board in the solid straight-grain range. Its best argument is a stiffness calculation: bending stiffness rises with the cube of section depth, so going from 25 mm to 30 mm multiplies stiffness by roughly 1.73×, while material and weight increase only about 11%.The 140 × 30 solid straight-grain board is for the briefs that ask for solid, deep and stiffness-per-gram: the straight-grain answer for heavy-duty ground installations and exposed, windy sites.