Kenko ND Filter PRO1D Smart Variable NDX3-450 Filter 67mm, for reducing The amount of light, Stepless concentration adjustment

I received the Kenko PRO1D Smart Variable NDX3-450 Filter with a 67MM diameter. Unfortunately I received a used item, even though it was bought new and shipped from Amazon. I returned the filter as it had imperfections in the glass and a small scratch. Otherwise, for the price it seems okay, but in a brief test, I noticed a warm color cast.One interesting thing is that the front of the filter is threaded and is larger in diameter to prevent vignetting. However, neither the Amazon description or the manufacturer website states what the front diameter of the filter is. Three stars for the filter, and 1 for Amazon for shipping used stuff, which is not uncommon.