My one complaint about the HJC RPHA 11 Pro helmet is that there is no Transitions shield available for it. One of the things I love about my Bell Star is that it has a Transitions shield which means one lens. The fewer lenses the better, right? Since I like the sun reactive shield so much I bought this for my HJC helmet. I peeled the protective film off my new HJC helmet and put this on first thing. I have never used pinlock system before but it's pretty easy to figure out. There are little knobs on either side of the helmets shield that turn. Just below the knurled knobs are cams that move as you turn the knobs. turn them so they are closest to each other, and put the holes in the overlay over the knobs then turn so the cams tension the overlay against the shield. There is a (silicone?) bead all the way around the overlay that (I think) prevents it from laying directly on the shield. Even with this second lens, optics were still very good except I found the bead around the edge somewhat distracting. It darkens in sunlight but not as much as the Transitions shield on my Bell Star. For that reason I'm giving it 4 stars and not 5.