If a gauge is sized at 52mm or 60mm is that the inside diameter (ie the size of hole you need to drill) or the outside diameter ??

Cheers

 

With defi's it's the inside dia. I cut mine with a holesaw, then carefully opened it to the line with sanding drum in a dremel, with loads of trial fits, until they are a tight push fit.

DON'T do what I did though! I forgot the pod was f/glass, and had f/glass bits through my jeans and round my thighs and nads for about three days

Alcazar