The baffles are built into e.g. air intake or exhaust ducts to reduce noise from the room or from a powerful fan.
Thus, they prevent the noise from being transported by the duct.
Order example:
Item no: Baffel 14000
Dimensions T x L x H
200 mm x 1200 mm x 600 mm
Measurement:
H = Height
T = Thickness
L = Length