Trim  is an auxiliary building material used for joint treatment of different materials in ground and wall engineering, which strengthens the stability of flat veneer of wood floor and floor tile on both sides through physical connection. Its core functions include restraining the deformation of materials caused by thermal expansion and cold contraction, reducing the risk of warping caused by the difference of expansion rate, and at the same time having decorative closing function. Common materials include aluminum alloy, stainless steel, plastic rubber, etc. Metal materials are widely used in the transition scene between tiles and wooden floors because of their strong pressure resistance.