I have the 420 egg bong and could NOT get a nasty, stubborn ring of resin just above the water line to go away when I cleaned it. After reading reviews for this I ordered the 2 Oz bottle to try it, but for some awesome reason that I am not complaining about whatsoever, I got the larger ‘bong’ bottle of cleaner instead. So thanks for that! :) It. Works. It’s goopy asf and it kinda looks like Slimer just got melted, but it works. Within literally 5 minutes of shaking the product around inside the bong and the goop covering its insides, most of the resin ring off had came off. After thirty minutes and a good hot water rinse it looked (**** near) brand new. There were a few small spots I still could not get off, but that’s where the Hemper pipe cleaning bristles (that I purchased with the cleaner because I had a feeling…it is an oddly shaped bong after all ) came in to finish the job. I had to tie two together and snaked them in but it worked! I also used the excess goop from the bong to soak the bowl piece in a bag. The goop looked disgusting afterwards, but my pieces are CLEAN!! Best cleaning product, bongs down!