I bought this to refurbish my V4 Sidewinder X1, and this was a perfect replacement for the old ceramic heater. The only thing I noticed, is its not clearly labeled which red wire goes to the relay and which is attached to the power supply. Even though this was a little perplexing, I just attached one wire to each component, and it worked flawlessly. I recommend doing a PID tuning to calibrate the bed, but otherwise was perfect.