Probably .125" or so. I was hoping for .100 or .090". Just got it an hour ago and it works pretty good if you don't draw on it to hard. If you hit it hard unburnt flower will go through. But nice. I need to practice more. :)
Really this is like a 1.5/2 hit bowl, even on my largest bong. It's nice when you have the time and take the time to clean after each hit so you always have the nicest green hits, but I think due to the shape and that you are burning to completion with almost every hit it does resin up quickly. The little nubs are great to have a cool spot to grab and as always feels like some thick glass, dropped it a few times and so far has just bounced!
420 science and helix grav products are awesome
It really is a perfect little one hitter, great for saving ****. It's so small you have to pack it like a cone. Overall it's just what I wanted.