The Types classification differentiates GDLs by substrate material and structural architecture, principally Carbon Paper, Carbon Cloth, and Metallic Mesh. Carbon paper GDLs, fabricated from microporous carbon fibers bonded to a polymer matrix, deliver uniform porosity and low electrical resistance, making them the preferred choice for high‑volume automotive stacks where cost efficiency is critical. Carbon cloth GDLs, woven from carbon fibers, provide superior mechanical strength and flexibility, supporting stack designs that experience frequent thermal cycling, thus finding favor in stationary power installations where longevity outweighs unit cost. Metallic mesh GDLs, typically composed of stainless steel or nickel alloys, offer exceptional thermal conductivity and corrosion resistance, catering to niche portable power applications that demand rapid heat dissipation and robust performance under harsh environmental conditions. Each type contributes uniquely to the overall market size by aligning material properties with specific performance requirements, enabling manufacturers to target distinct value propositions within the broader Hydrogen Fuel Cell Gas Diffusion Layer market.