3-1/2 3000 Series - Evolution LED. IC Air tight new construction housing for PAR16 LED Lamp. 18 gauge 0.051 (1.3 mm) thickness galvanized steel. Approved for installation in insulated ceiling with direct contact to insulating material (except polyurethane). Air Tight. Junction box can support up to 10 – 14 gauge wires or 8 – 12 gauge wires. Below-ceiling accessible. Cutout diameter: Ø 3-5/8 (92 mm). Can fit in ceilings up to 1-1/2 (38 mm) thick. Requires a 5-1/2 (140 mm) clearance beyond the ceiling level. Contrast hooks for ease of installation and a perfect fit to ceiling. Mounting bars extend from 10 (254 mm) to 24-1/2 (622 mm) to fit in most ceilling structures (compatible with suspended ceilings). No light leakage.