Designed for short bed trucks and extended cab short bed pickups, the Round Tube Slider provides additional turning clearance and prevents damage to truck and trailer in tight turning conditions at low speeds. Will not fit truck beds shorter than 6 feet in length or Flareside or Stepside. Check clearance between kingpin bed and tailgate before moving to maneuvering position.Note: This product requires the purchase of Universal Rails which must be purchased separately.Fits Reese and Pro Series 15K, 16K and 20K 5th wheels with rail pin width of 20-1/2 inches.Will NOT fit older models with rail pin width of 29 inches or Signature/Elite Series hitches.