I'm ordering a light soon (Streamlight Propolymer Luxeon 3C or 4AA) and was wondering what the physical differences are between regular flashlights and the upgraded safety rated versions. Are they built better or more reliable and why do they cost more? Is there an actual physical difference or are safety rated lights just regular lights that have been thoroughly tested and the ones that pass certain standards are labeled safety rated and the ones that fail are sold as non-safety rated? So the higher cost of a safety rated light - is it because of better materials or just the labor cost of testing the lights?