Originally Posted by Jon
Had the expensive genuine Leup one in my VX3, far better than a sunshade as it didn't alter the ranging.
Downside is it reduced the light 17%, but you get used to it. Only used it when raining.
Its been widely reported by others cheap kill flashs don't work too well.
I have a Leupold one which I use on my Premier Leupold Competition Series 40x.
I only use it when the sun is bright and to the front, it works a treat and I can range fine well with it, when without it I'd only see a white haze.