Peppering the inside of the guards with stones

[AlexCim]

How is everyone protecting their guards from being smashed to pieces by semi slicks / slicks and stones?

I've got a few nice spiders on my guards now from stones smashing them from the inside.

[AlexCim]

My only concern so far with a film has been it peeling off. So I'd prefer something that brushes or sprays on.