There are two Hi Force 44 solders, the regular is 4% silver and 96% Tin and melts at 475 degrees F., the Hi Force Hi Temp is 95 % Cadmium and 5 % silver and melts at 650 degrees F. It does give off gases and if I have to use it at all, I use it outside or with the windows and door open in the shop with a fan blowing. It says right in the instructions that you need to use plenty of ventilation with it. Bob