A hard nonresilient rubber formed by vulcanizing natural rubber
Else clues• Bowling ball material
• Clarinet mouthpiece material
• Comb material
• Comb rubber
• Common bowling ball material
• Electrical insulation material
• Hard black rubber
• Hard rubber
• Inelastic rubber
• Insulating rubber
• It would not be, i.e. soft rubber
• One bite of rubber
• Vulcanized rubber