Specification: This is solid state relay SSR-40DA. Model: SSR-40DA Input voltage: 3.2-32V DC Output voltage: 24-380V AC Output current: 40A Relay Size: 5.8 x 4.5 x 2.2cm / 2.2 x 1.7 x 0.8inch (L*W*H) Heat Sink Size: 8 x 5 x 5cm/ 3.1 x 2 x 2inch (L*W*H) Total Size: 8 x 5 x 7.2cm/ 3.1 x 2 x 2.8inch (L*W*H) Package Content: 1 x Solid State Relay SSR-40DA 1 x Heat Sink Matters Needing Attention: 1. The current on the product is the maximum load current, not the rated current. 2. On the basis of the different of the load character,you should keep the different allowance on the level of the current when you choose the product.(When the load is resistive, the load current should be 1/2-1/3 times of the max load current the load is inductive or capacitive,like motor， transformer， the load current should be 1/4-1/6 times of max load current.). 3. When Installation,solid state plater and radiator with smeared thermal conductivity silicone grease. 4. ≥20A With radiator, ≥30A with radiator and fan strong cold. 5.A small white package of thermal compound is for better heat dissipation. You can apply evenly on the heat sink when you install it.