Tube AUTHOR 700x18/25C. 100% all butyl rubber made with extremely air-tight. Keep air pressure in bicycle tyre longer than cheaper tubes made of syntehtic rubber. Presta valve 48 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 18/25-622/635. # inner tube FVphotogalleryproduct options Photogallery Product options black700x18/25C = UA#37270201