Batteries are considered dangerous and prohibited goods for air freight. 

Please do not order batteries if your destination country is not delivered by road transport from the Netherlands.

Maintenance free battery:

- maintenance-free or sealed battery needs NO refilling of electrolyte.

- minimal spillage and sulfur formation.

However, a maintenance free battery is still a Lead Acid Battery and needs to be kept charged also during periodes when the motorcycle is not used.

All lead acid batteries; irrespective of whether being VRLA Flooded, Gel, AGM & conventional flooded types are quick to charge to 70% of capacity within 2 or 3 hours, but this technology requires another 9 to 10 hours to “float charge” after the initial charge. If users fail to float charge, lead acid battery-type capacity is dramatically reduced. All types have a memory in that every time a user charges to less than 100% charge, battery capacity is shortened.

https://en.wikipedia.org/wiki/VRLA_battery