The Sanwa Denshi JLF-SP-R Red Tension Spring adds "weight" to the Sanwa Denshi JLF and JLX joystick lever series. In a default JLF/JLX joystick lever, it needs 1N force to move and compress the spring. The red colour represents 2N force so it needs twice as much effort. This makes every movement require more intention and less stress to return to neutral position.