uxcell Aquarium Straight Air Line Connector Coupler Clear White 4mm Tubing 10pcs Color : Clear White;Total Size : 23 x 9mm/ 0.9" x 0.35"(L*D); Connector Outer Diameter : 4mm / 0.15";Inner Dia : 2mm / 0.07" Healthy and non-toxic aquarium airline connectors are used for mending or extending air hose. Connectors combine two inputs to create one output which are excellent for use with dual outlet pumps. Great to use for connecting standard aquarium tubing airline. Aquarium tubing connector straight, they are made of good quality white plastic, non-toxic and durable.