There are two tufting types: flat wire and round wire.
Flat wire (also called anchor type), flat wire is inserted across the hole to hold bristle, see below picture:
Round wire (also called staple wire, staple type, and punch filled type), round wire is shaped as a u-shape and inserted in the hole to hold filaments, see below picture:
For staple wire, plastic blocks must be thick enough, otherwise brush blocks will be punched through by the U-shaped round wire; for flat wire, thickness of plastic block can be relatively thin.
One machine is designed as one kind of tufting system, either flat wire or round wire, cannot be with two kinds of tufting system for exchanging in the same machine.