Why a post base? Ever seen SIGNS pulled out and dumped in the bush by some one that counts it as a challenge. These bases are about lifting the bar. This base is designed to need equipment to pull them out.
The concrete post bases (above) make sure that the signs stay where they were put. These bases weigh approximately 50kg, when installed they engage with the natural ground in a way that prevents them from being manually lifted out. they must be dug out, this also makes them relocatable and reusable, but above all vandal proof.
The Steel base does the same job but it only weighs 10kg so is easier for handling. There are kits for installing them directly into the concrete path or median strip.