Celestion G12M Greenback Guitar Speaker, 16 Ohm With its well controlled low end it can be used singly or in multiples for use with high powered rock heads. An ideal speaker to bring drive and definition to modern high gain amplification. 12 inch electric guitar speaker available in 8 or 16 ohms. 12 inch electric guitar speaker available in 8 or 16 ohms. With its well controlled low end it can be used singly or in multiples for use with high powered rock heads. An ideal speaker to bring drive and definition to modern high gain amplification.