Tri-extrusions are commonly extruded in multiple configurations:
Tri-stripe extrusions are comprised of a primary polymer along with two additonal polymers that are used as stripes. Often used to make multiple stripes of a different color.
Multi-layered stripe extrusions have two layers of differing polymers along with the addition of a single or multiple stripes that are often colored or radiopaque.
Tri-layer extrusions are comprised of three different polymer layers. The inner layer is typically comprised of a lubricious polymer that can help reduce the friction between wires or other components that are inserted into the inner diameter of the extrusion. The middle layer is used to bond the inner and outer layers together to prevent de-lamination between the inner and outer layer polymers. The outer layer is commonly a material that has the ability to easily bond to other polymers during downstream assembly processing.