A WPC square stair tread (48" x 11.8" x 1.2") with a riser (48" x 7.9" x 0.32") refers to the specific design and construction of the staircase where the stair treads have a square-edged profile, and the vertical component between the treads is the riser which has the same color as the treads. WPC stands for wood plastic composite, which is a type of rigid core luxury vinyl flooring known for its durability, water resistance, and stability. The color representation of this product on the website may not precisely match the actual products due to variations in screen settings, lighting conditions, and natural material characteristics.