Enhanced Drying Capacity: Dry up to four 1kg 3D printer filaments simultaneously with the SUNLU Filament Dryer S4. Boost drying efficiency and printing quality even during printing sessions. The Four-Spool Filament Dryer Box is equipped with eight filament holes and PTFE tubes, meeting the demands for drying multiple filaments and enabling concurrent printing with multiple printers Fast Heating & Drying Evenly: Equipped with a 350W PTC heater and a triple-fan configuration, the SUNLU S4 Filament Dry Box ensures safety and superior heating efficiency. The interior heat is efficiently circulated with three fans, ensuring a more uniform heating process. Boasting a 50% increase over the FilaDryer S2, it delivers optimal filament drying conditions. Additionally, the S4 3D filament dryer achieves rapid heating up to 70 C in record time Auto Humidity Control: The SUNLU FilaDryer S4 incorporates a high-precision humidity sensor, displaying real-time interior humidity.