Battery for ITDB02 2.4D shield


I recently bouth a colour LCD screen ITDB02 (2.4D model, with SD port) with the ITDB02 MEGA shield (with RTC) for my Arduino MEGA,
but I can't see anywhere the specification of the battery I need for the RTC to stay alive. Can someone help me ?

Is it something like a 3V CR2032 ? There is a "28" embossed in the plastic of the battery holder, but l can't read anything on the SO8 chip itself.
The shield comes from but I couldn't get the info from them. Diameter seems to be 19mm.

I believe that common coin cells are all the same 3v. 2032 literally means 20mm dia and 3.2mm high. There are no 19xx, just 16xx and 20xx so it's probably 20xx. Make darned sure of the polarity of course but if it fits it should work. I know the