6mm arm diameter, 9mm threaded collar internal diameter, it is designed for tremolo bridge, with this arm, you can quickly adjust the string tension and change the tone, realize tremolo effects.6mm arm diameter, 9mm threaded collar internal diameter, it is designed for tremolo bridge, with this arm, you can quickly adjust the string tension and change the tone, realize tremolo effects.6mm arm diameter, 9mm threaded collar internal diameter, it is designed for tremolo bridge, with this arm, you can quickly adjust the string tension and change the tone, realize tremolo effects.6mm arm diameter, 9mm threaded collar internal diameter, it is designed for tremolo bridge, with this arm, you can quickly adjust the string tension and change the tone, realize tremolo effects.6mm arm diameter, 9mm threaded collar internal diameter, it is designed for tremolo bridge, with this arm, you can quickly adjust the string tension and change the tone, realize tremolo effects.6mm arm diameter, 9mm threaded collar internal diameter, it is designed for tremolo bridge, with this arm, you can quickly adjust the string tension and change the tone, realize tremolo effects.