Graduated neutral density filter

I bought an inexpensive set up recently to help with sunsets photos as it really ought to be a standard bit of kit in the average bag, I am trying two systems the first I picture below on my camera, the second a simple screw in type on which I will report later. The idea is to get the exposure of the sun more suited to the overall exposure of the rest of the picture and to provide some interest in the sky.

The filter fitted on the camera

one of three graduated neutral density filters 1x,2x,3x stops

The effect