M1x1.78 Buna-N O-Ring, 70A Durometer, Round, Black, Buna-N, 1.78 mm ID, 3.78 mm OD, 1 mm Width (Pack of 1000) Made of Buna-nitrile for use with a variety of fluids and hydrocarbons Durometer (hardness) of 70A Round cross-section provides a seal between cylindrical overlapping surfaces For use across a wide temperature range from -40 degrees F (-40 degrees C) to 212 degrees F (100 degrees C)