First and foremost: definitely cuts sodium flare down to extremely manageable levels. Context: I primarily use this to film working with boro. Didymium is a standard for glass working and it functions just as it should when filming or taking photos. Though not specified for borosilicate, the material does its job in reducing the bright yellow & orange flaring that occurs when glass gets hot enough. I would love to see more advanced formulas become available as a lens, as there are some really cool boro working lenses that take working visibility to the absolute maximum, far superior to didymium in that application. My only issue is that the glass itself is either too thick, or not set deep enough. Enough that the outer threading doesn’t quite take additional filters, like an ND, well. Rather, it’ll screw in and halt, but only at about half the threads in. It’s doable, but doesn’t fill me with confidence; even my lens cap doesn’t quite sit all the way in. Ultimately, this is probably the best filter you can get right now for glassblowing DSLR/Mirrorless camera work.