Tube AUTHOR 26x4,00-4,90. 100% all butyl rubber made with extremely air-tight. Keep air pressure in bicycle tyre longer than cheaper tubes made of syntehtic rubber. American valve 32 mm. Less air loss = having to inflate less. 100% quality control, each AUTHOR tube is individually examined at the factory to ensue air-tightness. ETRTO 100/130-559. # inner tube AVwhere to buyphotogalleryproduct options Photogallery Product options black26x4.00-4.90 = UA#37226011