Sprenger: Stainless steel spring designed for Micro XS pulleys. - - Stainless steel spring designed for Micro XS pulleys. Low weight of 3 grams. Suitable for : - 420 - 445 - 470 - 485 - 490 - 505 - Cadet - Contender - Europe - Flying Dutchman - Finn - Fireball - Koralle - Korsar - Laser - Lightning - Marauder - Moth - Open 5.00 - Open 5.70 - Optimist - Pirat - Ponant - Topper - Vaurien - Windy Spring