The John Deere M166197 is a genuine OEM extension spring designed for mower deck lift assist mechanisms across a wide range of John Deere lawn, garden, and compact utility tractors, as well as ZTrak mowers and front mowers. This spring helps counterbalance the weight of the mower deck, making it easier to raise and lower. Constructed from durable spring steel, it ensures reliable performance and a long service life in demanding agricultural and landscaping applications. Key dimensions include a length of approximately 95 mm and a coil outer diameter of 15.8 mm.