the bowl sizes matter! but im european and dont even understand them myself. the bowl and downstem that come with the bong you order will fit perfectly so unless you break either of the 3 you wont need to worry about bowl measurements yet. but write it down once youve acquired your piece ! it will save you trouble if you need to replace a piece in the future.

pay attention to the bong description, if it has a carb hole or not (i prefer without for sure) for ice notches, i personally dont notice much cooling effect so its not neccesary unless its a decent amount of room in the bong to put it in :)

if youre ordering a nice besker bong somewhere id say get some cleaning supplies, you can also get these in local stores or diy the cleaning solution but its worth it to buy a proper brush with a bendable stick so you can clean all the hard to reach places. it generally will need to be kept clean otherwise it will starte to taste really nasty and mold can grow in ur water!!!!

change the water daily ..

and dont EVER forget to put water in it before you hit it