Fujifilm HS-10 HS-11 HS20EXR HS22EXR lens is using 58mm size.
Hoya CIR-PL Filter 58mm
Hoya CIR-PL Filter 58mm with box. Click on the image to view higher quality.
Without CIR-PL lens, the reflection of the sky direct to the water.
With CIR-PL Filter, it won’t capture the reflection from the sky.
Gain more blue on the sky with CIR-PL Filter
More detail of the lens could be found in the official website of Hoya in here.