what size tubing

[c1377]

what size tubing fits over the inside of a drilled universal (3/5 gal) carboy bung?
what size tubing fits over the top of a Three-Piece Airlock

and what is the difference between thickwall and thinwall?

 

[FSR402]

I'm taking it as you are looking to make a blow-off. If so, you will be better off not using the airlock with a tube on it. Just jam a 1.25 OD hose into the neck of the carboy.