A very beautiful bong with a very unique perc. I've never seen a percolator quite like this one so I'm not 100% sure I've got the water level quite right. I have it quite high and it gives a very good chug without getting any splash back. I couldn't find anywhere what measurement the joint size is but after getting it in my hands I can safely say it's an 18mm. I may be stupid and it may say somewhere on the website but I couldn't find it. A lovely bing but keeping on top of cleaning will be a priority with this little chap. A wondrous bong!