Chosen Solution

I have a scala Rider Q2 Pro Multset when opening the battery marks 400 mA but does not show the volts. The charger that came with it has an output of 9 V and 0.3 mA. Which battery should I buy?

@biobraga that will be a 3.7VDC 400mAh battery. Look for something like battery model CS-SRD200SL