Patio door heater. Robust can be used as a step under the patio door (4 x 4 inch). No condensation build-up eliminates any condensation build-up from the patio door. Curtain of warm air creates a curtain of warm air to cover the glass surface, inhibiting cold air infiltration. Blank sections available for peripheric heating. Epoxy-polyester powder coat finish. 4 x 4 inch compact profile. Solid, 18-gauge steel cabinet that may be used as a step. Thermal protection with automatic reset. Full-length wire way. Single tubular, stainless steel sheathed element with boxed aluminium fins for improved heat dissipation securely fastened at its center, floating in nylon sleeves at each end, eliminating expansion and contraction noises. Built-in thermostat accessible without removing front grill (optional). Low voltage relay kit (optional).