Hi, No problem drifting in here at all. We're all friends... mostly. LoL. I haven't measured it exactly yet but I hear that is about 6 1/2 ml. I'll measure it another day to be exact and post it here. I have a Doberman Pinscher and she loves all kinds of antlers. I get them from my hunter friends. Great chew toy! If she gets tired with them I usually put them in boiling chicken or beef broth. Makes them taste and smell better.How many ml’s does the beserker hold with the bubble tank? Also what kind of dog do you have? Mine goes nuts for an antler, lucky my brother in law is a hunter so he always finds antlers while in the forest and shares the broken or beat up ones with my pup. There pricey and sorry for the thread drift.