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 TO3L - TO-3 Heatsink Rectangular Shape Photograph Features Suits TO-3 Devices Fluted For Better Heat Dissipation Easy Mounting Dimensions: Length - 32mm, Width - 32mm, Height - 60mm