TO-220 style Heatsink Insulator

Aluminum Oxide Ceramic construction
19.3mm tall x 12.7mm wide x 1.57mm thick

Thermal conductivity = 2.05 W/mK (at 100C)
More then 2x thermal conductivity of mica.

Works particularly well for high frequency applications
Use in place of mica insulator (still requires heat sink compound).
Manufacturer: Thermalloy