Standard, the PD-55 has a 98,4 mm round adapter. Optionally, additional adapters can be ordered for larger posts. A 107,9 mm adapter is available for larger round posts. For square posts, a 103,2 by 103,2 mm adapter can be mounted. Adapters are easy to change and attached by means of four bolts. The adapter can allow air to pass through at every corner so that the postdriver can not come off of the post when it is activated.