This filter is given as a free accessory when buying some Sigma lens models. For something that we get for free, its performance isn’t bad at all. It transmits only 0.5% of the UV radiation from the 390 to 200nm range. It has a high visible light transmission although we would have expected otherwise. It has a very small tendency for flares, which definitely is an advantage. If you have to pay more than the 200 Polish zloty list price for it as a separate accessory, you would be better off considering a better and cheaper filter from some of the other firms.