Originally Posted by
oneclick
The Park chrome (nickle only?) plated ones are 1.9mm.
The Hozan chrome ones are 2.3mm.
I did get two sets of thin-but-thicker spanners, metric and imperial, 3.4mm - they've been properly useful a few times.
There seems to be a lot of variability between brands. I just measured Campagnolo at 2.0mm, ATD at 1.6mm, and VAR at 2.5mm.