To drive in 4"x4" posts a pilot hole must be made in the ground first. A 2" pilot hole is the recommended size. If the ground is very hard or dry, fill the pilot hole with water and leave to soak before driving the posts into the ground.
Our Pilot Core Tool can be used to make a pilot hole, or alternatively an Earth Auger.
Internal diameter of 107x107mm. This adapter is suitable for driving 4x4" square posts.