The 4 ball connector gives a quick and secure connection while the in-line valve keeps the nose pressurized when disconnected and reduces whip. Z4B1414FMIC 4-Ball 1/4" x 1/4" Female to Male Industrial Coupler. This durable air tool accessory is made of zinc, and features a 1/4" NPT fitting along with a 1/4" snap-in style fitting for easy use, as well as a protective collar to prevent accidental disconnects.