The Sanwa Denshi JLF-SP-B Blue 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 blue colour represents 1.5N force so it needs 50% more effort. This makes every movement require more intention and less stress to return to neutral position.