This is a "sliding" baseplate that you can use on your desk drawer, it uses the legal size rails to slide or you can use the included Rail Guide to use it on the actual drawer to slide on.
it uses up ALL the Ender 3v3se print bed and wil need m4x10 heat inserts
im using it on this specific desk:
https://www.amazon.com/dp/B0CLGTZNYB?psc=1&ref=ppx_yo2ov_dt_b_product_details
The author marked this model as their own original creation.