Topeak Aero Wedge Seat Bag – Strap-on Small Black. The aerodynamic wedge shape lets these under seat bags slip easily through the wind while the internal pockets keep tools away from inner tubes and other delicate items.Weather resistant covered zippers keep contents dry1000-denier Cordura PlusFitting for taillight3M reflective strip for increased nighttime visibilityMedium: 7.5″ x 3.7″ x 3.9″Large: 9.1″ x 5.1″ x 5.5″