Duct Fan Silencer 4 - Duct Fan Silencer for 4" Duct Fan ventilation Each 340g pouch treats up

Each 340g pouch treats up to 68 plants

These highly porous large stones are lightweight

User-selectable acid or alkaline relay

Comes with GL45 screw cap to prevent leaks

Recommended for larger

Duct Fan Silencer 4 - Duct Fan Silencer for 4" Duct Fan ventilation Each 340g pouch treats upA duct muffler designed for use with inline fans in grow tents, bathroom fans and other HVAC applications. Features dual aluminum flanges to help absorb sound waves from fan vibrations and airflow. High quality neoprene foam in an egg crate pattern that will reduce fan noise by up to 50%. Galvanized steel body that is corrosion resistant and can withstand extreme temperatures. Duct Opening Diameter: 4 inches Length: 15 inches Weight: 2. 30 pounds