I've always liked the symbols used to indicate pole defects to climbers, a white arrow on a red field: https://www.lemproductsinc.com/utilities/utility-pole-ma

I've always liked the symbols used to indicate pole defects to climbers, a white arrow on a red field: https://www.lemproductsinc.com/utilities/utility-pole-marking-tags-2/defective-pole-tags/ https://www.lemproductsinc.com/utilities/utility-pole-markin... http://www.techproducts.com/new/op/markers&tags/everlast_phase.asp http://www.techproducts.com/new/op/markers&tags/everlast_pha...