Cutting boards come in three major categories: wood (including bamboo), plastic, and hard rubber.
This second dial was no more than a thin disk of hard rubber or bakelite, with a red scratch-mark on one side.
If we remove the jar of the cell, we find that it is made of hard rubber.
Being made of hard rubber, it will soften and become pliable if a sufficient degree of heat is applied.
Battery jars are made of hard rubber, and are easily broken.
All points of contact must be well insulated with glass, porcelain, or hard rubber.
The behavior of the hard rubber just mentioned suggested listening to it also.
Drawing squares or T squares, as they are termed, are made of wood, of hard rubber and of steel.
He took a hard rubber rod and rubbed it briskly on his coat sleeve.
If I rub a piece of hard rubber with a woolen cloth, the rod will become charged with static electricity.