Perfect Fit for Ego Trimmers: This Ego 3660582001 compression spring is compatible with models including ST1500, ST1500-S, ST1500F, ST1500SF, ST1500XY, ST1510S, ST1510T, ST1520, ST1520S, ST1530, and STA1500, enhancing the performance of your 15-inch string trimmers. Versatile Replacement Option: In addition to multiple Ego trimmer models, the 3660582001 spring fits various Ego AH series heads such as AH1300, AH1520, AH1522, AH1530, and AH1531. A single solution for maintaining your Ego trimmer heads. Compatibility Alert: Note that older ST1500F or ST1500SF trimmers may feature an AH1500 head, which requires a 3660650001 spring. Check if your trimmer has green alignment lines to confirm if this replacement spring is suitable. Durable and Resilient: Precision-manufactured for consistent performance, this replacement spring maintains excellent elasticity. It reliably returns to its original shape after extended use, ensuring long-term durability and reliable operation of your trimmer. Color: Black Material: Metal Package Contents: 4 x Trimmer Spring Replacement Note: The actual product may have slight color variations due to lighting and display differences. These variations do not affect functionality. Measurement tolerances may vary by +/- 1-3 cm.