Firm Construction: Made from good materials, this air filter cover base is engineered for wear and pressure resistance, effectively enhancing its longevity and reliability during operation. Compatibility: This air filter cover base kit is designed to fit multiple models, including for RY251PH, For RY254BC, For RY25PHEMC, For RY251PHVNM, For RY25CSEMCVNM, For RY254BCVNM, 25CC, 25.4cc String compatible.