This is a Raspberry Pi A+ enclosure that is designed with holes for the 25x25 Heatsink and ventilation on the top side. A hole has also been added for the snap-on mounting part and extra support lines for increased durability. This enclosure has a snap-on mounting part for Ender 3, making it easy to attach and remove the enclosure. You can find the 25x25 heatsink intended for this enclosure here: https://www.aliexpress.com/item/32846989011.html?spm=a2g0s.9042311.0.0.27424c4dZpcUsU