Combo Grad ND and 81

Title was supposed to say 81A.

Anyway, are there such filters made?

The reason is that I don't want to stack filters on my Olympus 21mm f/3.5 because when I tried it I could see the vignetting. I have a Moose Filter which is basically a circular polarizer and 81A combo so I was hoping someone made a Grad ND with 81A.

or a Grad ND with Yellow for B&W.

Thanks

I would check Singh-Ray. I know it isn't always a smart choice but there are times that I stack a Cir-Pol over a ND for water shots.

Thanks, Stephen. I'll take a look.

Someone inboxed me already and said that this filter probably doesn't exist and suggested that I could use a step-up ring to mount a larger filter thread which would not cause vignetting. I'll probably try that.