Weller PL100 PL Series Precision Conical Solder Tip, Thread-On for Standard and DI Line Heaters, 1/4" x 0.05" Thread-on and thread-in precision tips for standard & di Line heaters Pl series tips are solid copper, plated with iron all over, precision electronic (Pl153 and # 333 tips are bare copper) Nickel and chromium behind the Working surface Thread-on tips can be used with heaters 360, 362, 37Ug, 537S, 1237S & 4037S Thread-in tips can be used with heaters 535S, 1235S & 4035S