Specifications:- Overall Dimension: 17 11/16"" x 15 3/8"" x 11"" (45 x 39 x 28 cm)- Maximum Internal Length: 15 3/4"" (40 cm)- Minimum Internal Length: 11 1/4"" (28.5 cm)- Internal Diagonal Length: 16 15/16"" (43 cm)- Inner Height: 5 7/8"" (15 cm)- Bottom Plate Size(LxW): 11 7/16"" x 9 1/16"" (29 x 23 cm)- Bracket Length: 7 1/16"" (18 cm)- Capacity: 30 L- Material: Pp- Net Weight: 6.6 Lbs (2.99 kg). Package Contents:- 1x Tail Box- 1x Bottom Plate- 2x Keys- 2x Brackets- 4 Sets of Screws- 1x Manual. Notice: - Before purchasing, please measure your helmet size and make sure the height of your helmet is less than 9 13/16"".