for Ego Trimmers: This Ego 3660582001 compression spring is seamlessly compatible with models including ST1500, ST1500-S, ST1500F, ST1500SF, ST1500XY, ST1510S, ST1510T, ST1520, ST1520S, ST1530, and STA1500, enhancing the performance and of your 15inch string trimmers. Versatile Replacement Option: Besides a wide multiple Ego trimmers, the 3660582001 spring also fits Ego AH series heads like AH1300, AH1520, AH1522, AH1530 & AH1531. A single solution that catches all your needs for Ego trimmer heads maintenance. Compatibility Alert: Note that older ST1500F or ST1500SF trimmers might feature an AH1500 , requiring a 3660650001 spring. Check if your trimmer displays green lines for alignment to confirm if this replacement spring is suitable for your device. and Resilient: Manufactured with precision, the spring replacement spring maintains excellent elasticity. It effectively regains its shape even after extensive use, assuring you of its durability and reliability in keeping your trimmer in optimal working condition. The actual product may have slight color difference or difference, which not affect the use Colour:Black Material:Metal Package Contents: 4x trimmer spring replacement Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.