The world famous original OX Mainspring for up to 40% more compressed poundage than conventional mainsprings.
Fits BSA Lightning Airsporter, Mercury, Supersport, Superstar, Goldstar, Anschutz 335, Original 35, 45, 50, 38 RWS. 24, 27, 34, 45, 50, Relum, Air Arms (all models), HW85, HW55, HW50, Haenel, Lion, ASI CF 16/20, Webley Mk3 (if the spring guide is reduced by 20 thou), HW95, 98, 99.