Thank you. In the mean time. I just ordered some non approved Tiffen .9 and .6 ND screw on filters and Polarizer filter from BH with aluminum rings, thanks for the tip!! Also got a nice little case for them and a lens cap of the same size. You just have to put them on backwards (not sure if that kills the benefits of the pola). not sure on the weight.
I presume you're aware that you also run the very real risk of ruining the threads on the Inspire's camera lens.