Hello. Welcome to Futurlec. The electronic components Superstore. To find the component your looking for, either search by Part Number or visit the relative department. Need Help. TO-3 TO3B - TO-3 Heatsink Black with Side Fins Photograph Features Suits TO-3 Devices Heavy Duty Aluminium Solid Construction Dimensions: Length - 80mm, Width - 24mm, Height - 38mm