When I was looking for a Solid State Relay (SSR) to control the heated bed I bought one of these on eBay Solid State Relay SSR-40 DD DC-DC 40A 3-32VDC Input 5-60VDC Output Looked perfect. Fotek is a reputable brand and the SSR has a 60 volt, 40 Amps DC rating which should handle the 10 Amps for the Robo heated bed no problem. But when I connected it up and turned the heated bed on, you would not believe how hot the Fotek SSR was when I turned it off about 30 seconds later. Even the plastic case melted as you can see in the pic!!! So it must have reached a temperature of around 200C or more. There is no way a 40 Amp SSR should get that hot when all it is handling is about 10 Amps. Then I found this http://canada.ul.com/safetyalerts/u...nterfeit-ul-recognition-mark-release-13pn-52/ It turns out many of the so called "Fotek" solid state relays sold on eBay are fakes and will not carry the load. Obviously the FET inside the SSR has way too high an "on" resistance to handle 40 Amps. But it's not possible to see the components as the SSR case has been filled with some gunk. I am just posting this in the hope that others won't get caught out by the fake SSRs. And many of the SSRs sold on eBay under this "Fotek" brand are high voltage AC types. Obviously there is a safety issue if these are also fakes.