The solid state heating system of these guns assures constant glue temperature. Both guns are made of unbreakable nylon, have a 1/16" nozzle with a spring loaded ball-check valve to prevent glue leakage, use 1/2" diameter glue sticks and operate on 120V. Glue Gun is 200W and has maximum temperature of 410?. The No. HD200 Gun is C-UL Listed.