This document introduces NEC's SEFUSE (SM/G series) thermal cutoff, which is a small, solid, and reliable fuse that can be used under 0.5 A / 250 Vac. Recently added 3 and 5 ampere / 50 Vdc models are also available. It protects home appliances and industrial equipment from fire and accidents by opening the electrical circuit if it detects abnormal temperature rise.