Try this. Try and put a dime in the joint, if it doesn't fit its 14mm, if it goes in and then gets stuck its 18mm, and if it falls right through you got 29mm. My bet is that it is either 14 or 18mm, but post a pic that is the only way we can tell for sure
Looks like a 18.8 to me. See if your pinky can fit into it without any space, if it doesn't have any room it's 14.5 if it has a lil space it's 18.8. Good luck.
If the dime doesn't fit its a 14.5, if it was a 18.8 the dime would be able to go fully into the joint before getting stopped by the bottom of the joint.
just how big the opening is, and that is definitely a 14.4mm or 14mm or 14.5mm.... theres three sizes for GonG.. 14mm, 18mm, and sometimes 29mm........ my whole pinky can go into my 18mm joint, only the tip of my pinky can go into my 14mm joint...
You could get a ruler...oh wait Americans don't use the metric system. But yeah if your pinky can hardly fit in its probably 14mm
There is actually more than 3 sizes, but in this case only 14mm or 18mm would apply. Why don't you just measure it though, 14mm is pretty small, 18mm will fit your thumb.
post another pic that isnt as zoomed in as much. But that dime trick is basically fail proof lol. Also, make sure you r measuring only the inside of the joint and not the lip as well because I think thats what you were doing if the dime didnt fit in the joint and you just measured it to b 18mm...something isn't right
If the dime wont fit into the bong its a 14.5. if it was an 18.8 the dime would be able to lay FLAT inside the joint without falling through.