Review on Easycargo Insulator Rubberized Transistor 20Mmx15Mmx11Mm by Johnny Bloomer

I use them to cool some PWM FETs on a hobby board. They lowered the temperature from "burn fingers" to "too hot to hold." With a little cross ventilation they are just warm. The threaded screw hole is comfortable to the touch and eliminates the hassle of fumbling with a nut on the back. These are not large heatsinks and do not solve serious overheating problems. But they do what they're supposed to do. Unfortunately, there is no information in Celsius/Watt for either tRca or heat output. Look elsewhere for specs or use trial and error.