What are they? As on another server that is well-known there is a feature called a "Chunk Hopper" this is basically a hopper that collects a certain crop/mob drop in the chunk, the chunk hopper is then connected to a chest without the use of any other hoppers. Why should you add it? It is proven to prevent less lag, and saves players from either crafting and spending resources on lots of hoppers and it reduces ugly hopper lines all over the place. Conclusion I think you should really consider chunk hoppers as they would be very beneficial and would change how mob grinders are.