Hello, Isabella! Yes, the OSI-RI-FL is a suitable replacement for the Fire-Lite BEAM355. It is compatible with the existing wiring and mounting configurations, making the transition process smooth and hassle-free. Our technicians at firealarm.com have tested and verified its compatibility in various setups. Rest assured, you can trust the OSI-RI-FL to perform reliably just like your old BEAM355. If you have any specific questions or concerns about the replacement process, feel free to ask!