I cant remember exactly what it was called. Last year I searched the molded in part number on the box. It came back as part of the evap/emissions system.
This was on a E450 chassis.
Edited to add.
Found the part on fords parts site. It is the fuel vapor canister, definitly part of the evap system.
2021 Newmar Baystar 3401
2019 Jeep Trailhawk toad
2017.5 Forester 3051S Traded 7/2020