One hex baseplate for the hex floor tower (GHP104 or GHP105).
The base plate measures 148mm across the flat sides. Each baseplate has the slots needed to fit risers into place, and helps with adding walls and ladders to the bottom floor of your towers by providing a more solid ground floor structure (compared to just using the riser feet as supplied with each tower floor kit... so, these are designed to be used instead of the riser feet.