there are other numbers but are not visible. this thing looks like a metal cylinder, one end of the cylinder is pointed epoxy and there are leads out each end. it is in the shape of a diode but with one pointed end and the housing is metal.
Just in case you're not familiar with these, they put them in heating devices like coffee pots and such so that if things get to hot, they open the circuit and keep the house from burning down, they DO NOT reset.