This Leica Lens Hood is designed for use with the Leica Vario-Elmarit-SL 24-90mm f/2.8-4 ASPH. Lens. Lens hoods are primarily designed to block unwanted stray light from appearing within an image by extending and shading the end of a lens. Since the end of the lens is extended while using the hood, some extra protection from accidental impact is also provided.
I bought the very expensive $199 replacement hood from B&H, and I was assured that it would stay on the lens by B&H. During a ten-day photo trip, it fell off no less than twenty times. All it takes is a little bump and it will come off. But, I still have it because I attached a lens cap holder to the hood and looped the other end around the lens mounting area. Do the same or something similar or you'll regret it.
It's expensive but it's The OEM hood so, it is what it is