The SR540 is the newest addition to the SR family of coffee roasters. Roast capacity is 4 scoops, 120 grams. It has an improved control board. All adjustments are made with pushing the knob and turning to adjust the heat, fan, and time. It also features a real-time temperature read out. A quick turn of the knob to the right will display current temperature. There are now 9 levels of heat adjustment compared to having a Low, Medium, and High adjustment. The fan also has a wider range of adjustment. The chaff basket and top lid from earlier SR roasters will not fit on the new SR540. The roasting chamber is a much larger diameter. Users are also able to change the default start settings. These are only 120V and have a 1-year warranty. Warranty is void if shipped outside of the US.