Top case
Size: 39 X 29 X 38 cm - 28 LITRES.
The top case is in polypropylene, it is resistant and stiff. It consist of a fixation plate adjustable for motorcycles and scooter. The plate has quick release for a better practicality. Equipped with two keys for the manual clousure.
It is possible to insert 1 helmet inside of it and its maximum transportable weight is 3,5kg.
A fair compromise for your needs.