The y1 has had a slight rub with some wet dry multiple stages of grit mounted to a glass panel.

The y1 has had a slight rub with some wet dry multiple stages of grit mounted to a glass panel.

Does anyone know the differences between these 2 different heads? Please shed some light... been online looking for some time now and cant tell..
I can see the that one has "fins" o the bit below where it says y-1/3
See pictures below(if ii get this upload right!)

