Polypropylene Plastic.Please clean before install it . Replacement plunger rubber gasket for coffee maker Per package 2pcs plunger end , the other one can be saved for use as a replacement for use . Easy To Replace: Simply pry off the old plunger end and replace it with the new one - you're ready to make another satisfying cup! Plunger Rubber Gaskets are designed and manufactured specifically to be compatible with coffee and espresso makers for a , every use Not parts.meeting or exceeding the quality of plunger ends.