Item Type: RC Water Cooling Jacket Material: Aluminum Alloy Color: Black Specification: Length: Approx. 25mm / 0.99in Outer Diameter: Approx. 25mm / 0.99in Inner Diameter of Faucet: Approx. 3mm / 0.12in Application: Motor with an Outer Diameter of 20mm(Approx. 20mm / 0.79in)Package List 1 x RC Water Cooling Jacket1[Specially Designed] This RC water cooling jacket is suitable for 2030 motor and for 2040 motor, with outer diameter of 20mm. 2[High Quality material] This water cooling kits uses high quality aluminum alloy shell, with high strength, not easy to be damaged. 3[Copper Pipe Water Cooled Heat Dissipation] Using copper pipe water cooled heat to make the motor work longer and more stable. 4[Simple Operation] The RC motor water cooled jacket is very easy to install and disassemble, you can use it very conveniently. 5[Specification] The specific length is 25mm, the outer diameter is also 25mm, and the inner diameter of faucet is 3mm.