Be careful with it...
Ammonium bifluoride:
Air & Water Reactions
Dissolves in water and forms a weak solution of hydrofluoric acid.
Fire Hazard
Special Hazards of Combustion Products: Toxic ammonia, hydrogen fluoride, hydrofluoric acid, and hydrogen gases may form in fire. (USCG, 1999)
Health Hazard
Inhalation of dust may cause irritation of the respiratory system. Ingestion causes irritation of mouth and stomach, vomiting, abdominal pain, convulsions, collapse, acute toxic nephritis. Contact with dust irritates eyes and may cause chemical burns or rash on skin. High concs. of fluorine in the urine have been reported following skin contact. (USCG, 1999)
Reactivity Profile
AMMONIUM BIFLUORIDE reacts violently with bases. In presence of moisture will corrode glass, cement, and most metals. Flammable hydrogen gas may collect in enclosed spaces. Do not use steel, nickel, or aluminum containers [USCG, 1999].
Above info copied from -
http://cameochemicals.noaa.gov/
This is really a great site for chemical users. You can find physical properties, reactivity, emergency response procedures, and more.