Product information: Seatpost spring, bike guard, eliminates bumps on cycle paths and city streets. Seatpost spring function: very smooth ride on rough roads and less fatigue. And this spring is strong enough to hold more than 200 lbs. COMPATIBILITY: The Universal Seatpost Spring is compatible with all SR Suntour NCX seatposts, fits all post diameters, and reuses the original spacer inside (if available). Reliable Material: The NCX seatpost is an excellent suspension seatpost - especially for ebikes without rear suspension. However, if you weigh more than 200lbs, it will not support your weight and will bounce up and down like a spring-loaded single stilt. Even if you max out the spring tension, it won't help. But this red spring is designed to take the extra weight and is easy to install and adjust! Perfect after-sales: we will provide you with quality and performance guarantee, if you have any questions about our seat post springs, please feel free to contact us by email, we will give you a satisfactory answer within 24 hours!