I'm selling a camera for my neighbor and I'm not sure exactly what it is.

I thought it was an 8"x10" but the insert appears to be 5"x7". Is this for regular film?

The lens is on a 9" board, it's about 8" long but has no focal length markings, just "Special Rapid Portrait Series 3".
It appears to start at f1.6, is that even possible?
GG is 9"x10".

It has the name Marynen on the front standard

I'm a bit stumped, any clues would be appreciated!