Fantech FR 100 is a 4-inch inline centrifugal duct fan for small to medium supply or exhaust runs. Its UV‑resistant thermoplastic resin housing allows indoor or outdoor installation, and a mounting bracket and external wiring box are included. The unit connects to 4 in round ducting, is HVI certified and ENERGY STAR, and carries a 5‑year factory warranty. Free‑air performance is about 151 cfm, with roughly 123 cfm at 0.2 in. w.g., suitable for general ventilation or makeup air assist. The motor includes built‑in thermal overload protection and the fan is rated for airstream temperatures up to 140°F. FR series models are not intended for radon mitigation; choose a dedicated radon fan for that application.