These bolt-on, big bore, position sensitive internal bypass shock absorbers have been developed and tested to provide exceptional ride comfort around town with significant amounts of end-zone damping for exceptional chassis control and handling off road. BP-51 shock absorbers provide greater levels of damping at each end of the stroke based on position and velocity of the piston. This provides a comfortable and compliant ride during normal driving, improved control over challenging terrain and prevents harsh topping/bottoming out through bumpy roads. Damping performance is easily adjustable across a wide range in both rebound and compression, allowing the driver to customize the vehicle's ride performance for road conditions, vehicle load scenarios and personal preference. The body, reservoir and components are all made from aircraft grade (6061 T6) aluminum, with a type 3, 40 micron hard anodized finish, ensuring exceptional heat dissipation and resistance to corrosion and stone damage.