SJCAM SJ8 Pro lens diameter

[arimak]

I'd like to use some accessories for my camera which has 20mm diameter, so I'm looking on ebay,.. for something similar
so my question is what is diameter of SJ8 lens, I guess it will be something like 20-25mm.

[czaroslaw]

21mm
You can find dedicated filters for sj8 diameter 40.5 with adapter 21 -> 40.5