This is a Silica Gel Box and also a filament retraction device. Using magnetic gear, filament can be retracted without opening the drying box.

With a generic 5.8L dry box , it's compatible with most spool(including Banbu,Sunlu,Jayo,Tinmorry).The 4L dry box has not been tested, but adjustments can be made according to the actual situation by resizing the overall dimensions using Bambu Studio or directly cropping the central part of the Silica Gel Box to make it compatible.

By removing some support to achieve compatibility with diameters of 15mm, 12mm, 10mm, and 8mm magnets.It is recommended to use magnets with a height of 5mm, which can also be stacked to reach 5mm. The number of magnets is configured as 15mm*3 or 12mm*3 or 10mm*6 or 8mm*6 (excluding magnetic gear).