This direct vent wall pass-through thimble is made by Harman and is listed as a compatible venting component for Harman pellet stoves and inserts when using Simpson Pellet Vent Pro pellet venting.

More Information: 

• The exhaust opening will accommodate both 3" and 4" vent diameters and a 3" outside air flex hose.
• The term "direct-vent" means that this thimble supports exhaust venting AND an outside air connection all in one
• Supports the outside air temperature probe for stove models with a touchscreen controller
• Requires only one narrow opening for installation, 7 1/4"~7 1/2" square
• Tough 316T stainless exterior with low profile intake hood
• Can accommodate a nominal wall thickness between 4" and 10 5/8"