Glass Thickness Measuring Devices.

[tomba26]

Can anyone recommend a decent glass thickness measuring device, one that will give overall thickness of double glazed units?
I've seen/used the plastic caliper type but really I'm after a decent handheld unit that I can use without having to have the windows open...kind of point and shoot and you get a reading. It will be used on a regular basis.
I know Merlin do one, anyone used that or anything else similar?

Thanks.

 

[crank39]

I believe merlin are the only ones that make anything like that, I have all 3 in the kit box type thing and wouldn't be without them