The Built to ISO Standard 4184. SP> They>These V-belts also have the UniMatch > This> Non-standard> SP>Example: SPZ512.NOTE:Belt> Example: XPB1400. For>Although metric V-belts are generally designated by section and datum length, they are sometimes labeled with the section letters, belt length in millimeters and the letters “La” (approximate length), “Li” (inside length) or “Lw”> Care>