My small experience with PolarCell battery...
Preview:
In the last year I have had a many unexpected reboots... From update to update it was less or more..
Tried different tips like a paper, cleaning contacts, trick with pins... But it not really helped... And I still got reboots almost every day and 1-2 in the day in different conditions...

PolarCell battery:
First impression was that phone feels like a new... For now 4 days with the same usage and same conditions like before but without reboots
Really like this battery, think to buy additional one as spare if current one going to be my primary battery.