When you refill a LEXMARK 64004HA, 64015HA, 64015SA, 64035HA, 64035SA, 64404XA, 64415XA, 64435XA, X644A11A, X644A21A, X644H01A, X644H11A, X644H21A, X644X11A or X644X21A cartridge, you must replace the chip. This chip is already included with our refill kits.