The 20/40 watt switchable temperature setting allows you to solder either electronic circuits or heavier jobs. It is ideal for both professional and do-it-yourself projects. NOTE If units are reported as smoking the smoke is normal. It is burn off of an anti-rust oil used when these are produced. The smoke should dissipate after 10 minutes; that is an approximate timeframe and subject to the volume of oil in the heating element which cant be observed or measured on the final product.