| MR1 |
|
Low Pressure Drop, Class I, 250°F / 350°F, 1½ hour Fire Resistance Rating |
| MR2 |
|
Low Pressure Drop, Class II, 250°F / 350°F, 1½ hour Fire Resistance Rating |
| MS1 |
|
Class I, 250°F / 350°F, 1½ hour Fire Resistance Rating |
| MS2 |
|
Class II, 250°F / 350°F, 1½ hour Fire Resistance Rating |
| MA1 |
|
Class I, 250°F / 350°F, 1½ hour Fire Resistance Rating, Airfoil Blade |
| MA2 |
|
Class II, 250°F / 350°F, 1½ hour Fire Resistance Rating, Airfoil Blade |
| MS1G / MS2G |
|
Class I/Class II, 250°F / 350°F, 1½ hour Fire Resistance Rating, Front Access Damper for Grille Installation |
| MT1 |
|
Class I, 250°F / 350°F, 3 hour Fire Resistance Rating |
| MT2 |
|
Class II, 250°F / 350°F, 3 hour Fire Resistance Rating |
| LA1 |
|
Class I, 250°F / 350°F, 3 hour Fire Resistance Rating, Airfoil Blade |
| LA2 |
|
Class II, 250°F / 350°F, 3 hour Fire Resistance Rating, Airfoil Blade |
