CliffCLIFF is a manufacturer of a variety of audio connectors and components.
Nut - Cliff, Hex, for mounting ¼" Jacks
Nut - Hex, for Cliff UK Jacks S-H902, S-H903, S-H904, & S-H905
Nut - Cliff, Hex, Red, used on Loudspeaker Output Jacks
Red Cliff hex nut, often used on guitar amplifiers to identify loudspeaker outputs.