Model 400 Retro Fit Dryerbox® - For existing construction - to be retro fit into an existing drywalled 2X4 wall. It is white powder coated and does not need to be painted. Does include a shoe-horn like tool to assist with the install. Make sure you review the instructions at this link before purchasing as there may be obstacles and special tools needed.
 

• 22 gauge aluminized steel, click here for enlarged image
• Powder coated (similar to finish on dryer appliance)
• Top port measures 4 7/8" x 3 1/8" oval shape
• Distance from mounting flange to rear of box is 4"
• Overall measurements: 21" h x 11 1/2" w x 4" deep
• Inside measures 9 1/2" wide x 18 1/4" tall
• Two mounting 3/16" holes on bottom flange
• Curved shoehorn like assistance tool included (see video)

Links:
Pictures of other installs  
Dimensions  
Instructions 
Alternate Installation Method Video

Also, be sure to check out the paintable (non powder coated) model available at select Lowe's and Menards locations.