To travel with us, it is mandatory to have a travel insurance.
We personally rely on two different companies; Generali and  Europassistance, which offers insurance policies also for few days with h24 assistance, advance payment of all medical expenses and repatriation coverage.
Both are very good companies and we personally recommend them.
 

If you want to check more insurances, you can have a look also at World Nomads, Columbus and Travel Gate.