X4 Labs™ Extender Accessories

3900 Gram Medium Tension Springs

Our specially calibrated 3900 Gram Medium Tension Springs provide the second highest amount of tension offered by X4 Labs™. Our 3900 gram springs allow you to perfectly calibrate your tension to your ideal number.

Whether you would like to give your lower tension Penis Extender a boost or would like to lower your maximum tension Penis Extender traction this is the spring set you need. All springs are scientifically calibrated by X4 Labs™ to guarantee the perfect amount of tension every time.