This is a high quality steering actuator rebuild kit, these steering assist assemblies were build with faulty rod shaft seals. The Larger seal that ride on the anodized surface does not come in this kit and if they were to have failed you will have bigger problems from the surface that it rides on. We used a Viton wiper seal and a High Grade Urethane Oil Seal for this kit. These materials are very expensive and will hold up for 20-30 years. We also included a piston seal for the cylinder that uses a O ring-seal on the plunger do not remove or replace the Brown piston seal on your plunger these do not fail as they are made of bronze impregnated teflon. Also note this kit will not fix a cracked plastic plunger as this is very common on this assembly. Most have cracks in them but this wont necessarily hinder performance depending on how severe the cracking is. The reality is mostly all of these are cracked but they still function properly perhaps a little stiffer or slower but its worth a shot in rebuilding it vs replacing with a new assembly for $650 that will have the same issues.