11. Until recently, electronic drums were small solid pads made of hard rubber or plastic. 12. Stick to hard rubber and softer nylon type chew toys. 13. "They just don't make hard rubber anymore, " he said. 14. Ditto sheets of hard rubber more than an inch ( 2.5 centimeters ) thick. 15. Depending on the sulfur percentage hard rubber has a thermoplastic transition or softening temperature of. 16. When the war prevented import of eyeglass frames, demand for his hard rubber frames skyrocketed. 17. The hard rubber projectiles hit the chins and elbows of children playing at the party. 18. It was made of two parts and contained a hard rubber insert and brass reed. 19. In general, hard rubber bones and other latex dog toys help improve dogs'overall oral hygiene. 20. He has a handful of Chinese-made mitts and a bagfull of battered hard rubber balls.
