Phillips, Truss, Plastite-Alternatives. Thread Rolling Plastite 48-2 screws are used in thermoplastics, engineering resins and certain thermosets. The 48° thread profile increases holding strength while reducing material displacement. Truss head screws are weaker than pan or round heads but preferred in applications where minimal clearance exists above the head. Modified truss heads offer low clearance and an extra large bearing surface. Commonly used to attach metal lathe to metal studs.