This thing is pretty cool & does what it is meant to do. The only down fall I see is that it is plastic. Might not be an issue if it were a snap on, but due to the very very fine threads on the ARD & the aluminum threads on the SPARC it could be quite possible to cross thread if your not careful.
Pros: Prevents reflective lens glare
Cons: Plastic
This review was written in the old system and had content requirements that are different than reviews written today.