The Vauban style of fortifications was very complex and had many elements. Two of the most important elements were the bastions and the walls. The bastions and the walls have to meet at a precise angle to fit together properly. This requires the Bastion Connectors provided in this kit. This kit has enough connectors for four bastions. NOTE! This kit is ONLY necessary if you are using bastions from the PaperTerrain Vauban 4 or 5-sided Fort kits. If you have purchased bastions from the PaperTerrain Vauban City Walls kit then you do not need to buy this kit as the bastion kits come with the necessary connectors included. This kit comes in either brick or stone finish.