Slate calls are most of the time a more smooth call with great tone and great for low sounds like tree calls, purrs and soft yelps and more volume if you need it. Glass is a louder more raspy tone great for cutts, fly downs, loud clucks and loud yelps. Both calls can be made water proof by using a water proof striker, the striker is what makes them water proof. Also try different strikers with slate or glass calls can make a world of difference in the sound and tone of the call. I carry a slate and glass call. Cody and primos jakepot calls sound great.