Tube AUTHOR 27,5x1.75-2.35. 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 40 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 47/60-584. # inner tube FVwhere to buyphotogalleryproduct options Photogallery Product options black27.5x1.75/2.35 = UA#37227201