ZETA Racing Pre-Load Adjuster. Quick preload adjustment by turning, not tapping! Simply insert it between the stock spring seat and spring for improving work efficiency. Even in a bike where access to the rear shock is difficult, adjustment can be easily made by simply turning the spring part by hand without using special tools. Facilitates difficult preload adjustment without damaging the plastic spring seat. Materials: Body - High-strength aluminum alloy, Teflon ring - Teflon. Includes: Spring seat x one (1) piece. Washer x one (1) piece. Teflon ring x one (1) piece.