GrowLite’s Tru Blue Open Rated Metal Halide (MH) Lamps & Bulbs are designed and manufactured to GrowLite’s own custom proprietary specifications. All of GrowLite’s Tru Blue Metal Halide lamps are Open Rated for safety. Tru Blue MH bulbs are the industry’s first and only Open Rated lamps. We believe in customer satisfaction. GrowLite backs Tru Blue MH lamps and bulbs 100% with a one year full warranty.