Adds 1/2" front end ride height to Jeep JK Wrangler (2 door), and JK Wrangler Unlimited (4 door) 2007-2018 Set includes 2 pieces. Height is 1/2", Inner Diameter is 2.5", Outer Diameter is 5.125" Install between Jeep frame and rubber spring isolator (on top of spring). Install time is 1-2 hours, jack and wrenches are required. Stack additional units to attain different heights. (Up to 2 inches of lift can be obtained with multiple front spring spacers.) Made from the toughest available semi rigid urethane to absorb impacts and pressure. 5 year warranty from date of purchase. (Replacement spacer provided to original purchaser if the spacer fails while installed as advised on Jeep suspension.)