What is 6.35?

6.35 usually refers to the size of a standard guitar jack or plug, which is also known as a "quarter-inch" plug. This type of plug is commonly used in musical instruments and audio equipment, such as amplifiers, pedals, and some headphones. The measurement of 6.35mm is equivalent to 0.25 inches. Some other common uses of 6.35mm measurement may include plumbing fittings, hydraulic hoses, and pneumatic systems.