Bandit signs on metal poles

[Lou Forino]

I have been starting a bandit sign campaign in NYC. An issue here like some other parts of the country are that most of the main roads have metal lights and no wood poles. We have been using electric zip ties to secure the signs, but I see some pros (the cash for car guys) using some type of black adhesive.

We are looking to speed up the act of putting up the signs and I was wondering if anyone has any experience using this black adhesive, know where I can get some and any other tips.