Minor annoying odd rant time for moi.
Is this the only set of rules (other than Gygax's odd basing convention which used 3/8" in some cases I believe which I find just as odd

as 13 mm) that uses non-multiples of 5 mm? Why? Is that meant to be an equivalent or an approximation to 1/2 inch?

I am unsure if his origin is American or UK/Canadian/Australian which would probably be the basis of mm versus inches? <insert duh on me icon here>
If he is American, why not just use inches and fractions like Gygax did? That would be understandable odd.

If he is not American - like most of he world, why bother with 13 instead of 15? Basing width 'per figure' is "trendy nerdy" but seems to be overly 'scientific' in it's approach. I rather doubt Barbarian hordes were so disciplined and all basing is an attempt to approximate the area a group occupied geographically. Almost seems like porting over 7YW/Napoleonic basing conventions to the Ancients arena.
Okay, odd thought moment has passed. Back to "important" questions like lace style on Austrian grenadiers...

Gracias,
Glenn