Makani Walu 2x8cm
Bought in January 2017 together with a set of 10cm
The 8cm makes a board much more like a single fin fern. At 10cm, it's more of a thruster.
In some circumstances it is nicer if the board runs a bit looser over chop, then the 8cm thrusters are well compromised between real single fin and thruster.
My standard configuration is 10cm, in fine waves definitely better. But if they are not nice conditions I use these 8cm fins.