Charging the vest for 30 minutes in sunlight will allow the vest to glow-in-the-dark for approximately 8 hours. Hi-Vis Surv 2Tone Safety Glow Vest-Grn-2X The Radians SV6GL Glow-in-the-Dark Safety Vest is perfect for mine workers, construction work that extends past sundown, parking lots, shipyards, cruise ships, or anywhere that there will be limited light needed for reflective tape.