I looked at the page for the Lanzar speakers and it doesn't say anything about them being waterproof. One of the main reasons folks use the Polks is that they are MARINE rated speakers that are good for use in external, rain/water exposed environments.
Fred.
I bought the Polks for installation ease since others blazed the path before me.
However the Polks are no more marine rated than most good automotive speakers.
The Lanzars are built with the same cone, surround and frame material..
The Polks come with Stainless steel screws. But, we don't use them. So in reality it is more of a size and instruction issue than a material composition.
Side note, It was very disappointing to sacrifice working drivers to use as a spacer