Airline Tubing : 4 m in length, and Inner diameter 0.4cm, outer diameter 0.6cm Clear and Flexible material. Desired length for most fish tank,flexible, and kink-resistant. 2 Stone - Airstone can be easily driven by pumps. Suitable for aquarium, fish tank and hydroponics.They are durable and can produce bubbles continuously to diffuse oxygen efficiently in your fish tank. 6 Suction Cups and 2 Check Valves - Suitable for inner diameter(4mm) soft tube, stick tightly to the smooth fish tank. You can put the red check valve in the airline tube between pump and aquarium water to prevent water from back siphoning. 10 Connectors (Straight & T-shape & L-shape etc.) - Perfectly connect standard tubing, T-connector allows you to combine two inputs to create one output with dual outlet pumps.Straight connectors will apply for mending or extending hose. Material:PVC colour:Transparent Package Contents: 2 x stones 2 x Opening / closing valve 1 x 4 m Standard airline tubing 2 x Check Valves 6 x Suction cup clips 2 x L-connectors 2 x I-connectors 2 x T-connectors 2 x X-connectors 2 x Y-connectors Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.