Tube AUTHOR 16x1.50-2.20. 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 32/57-305. # inner tube AVwhere to buyphotogalleryproduct options Photogallery Product options black16x1.50/2.20 = UA#37216001