High-quality material: Made of ABS and carbon steel, sturdy and durable, long service life, good stability, shockproof, cold-resistant and oil-resistant. Easy to use: Install the included spring on the spool cover in the bottom slot of the trimmer, press and turn the spool cover until the latch clicks into place to complete the installation. Sufficient quantity: The package includes 4 trimmer spool covers and 4 spool springs. The quantity is sufficient for your daily use and replacement. Good compatibility: The replacement spool cover size is 85 x 32 mm, the spring size is 23 x 36 mm. They are compatible with most lawn mowers on the market, such as: E.g. AFS GH400, GH500, GH600, CST1000, CST2000, NST2018, ST7000, etc. Scope of application: The valve core cover is suitable for patios, lawns, courtyards, gardens, crops, landscaping, etc. Ideal for replacing old or damaged valve caps and springs. Valve core cover - Made of high-quality ABS + carbon steel, good stability, impact