Based on this product's specifications, here are some alternatives and similar models
Filament Detector Sensor for Flashforge Guider 3 — compatible with model 20003721001
Summary description:
Filament detector sensor designed for use with Flashforge Guider 3 printers, compatible with model 20003721001. The sensor monitors filament presence and can pause prints on runout or break events to prevent failed prints. Intended as a replacement or spare part, it ensures more reliable long prints and reduces material waste by detecting filament interruptions.