Heat sink provides long lasting usage, it will help dissipate the heat and protect your relay. Easy installation: Made of durable aluminum material, mountable heatsink design, size, easy to install.need to be evenly coated with thermal grease between the solid state relay and the heat sink. calorific value: Actual load current (Amps) x1.5 / . Fit for: solid state relay -10A,25A,40A. The temperature of the solid state relay and the Radiator Module (contact with the heat sink) must not 80 Celsius. Product name: aluminum heat sink. Size: 8*5*5cm colour: black Material: aluminum Note: the solid state relay is not included. Package Contents: 3*Solid State Relay Heat Sink Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.