The 21” Universal Non Condensing Vent Kit 223182 is a water heater venting part designed by Rinnai for tankless water heaters and boilers. It features a white color and dimensions of 8.5” height, 33.5” length, and 7.5” width, making it compatible with various Rinnai models. This vent kit is lightweight at 6 lbs and is a crucial component for maintaining proper ventilation and functioning of your water heating system.