When sourcing uniforms with reflectors, the most critical standard is EN ISO 20471 (globally recognized) or ANSI/ISEA 107 (for the US market). These standards categorize garments into Class 1, 2, or 3 based on the area of fluorescent material and reflective tape. You must ensure the reflective coefficient (R') of the tape meets or exceeds 330-400 cd/(lx·m²) to guarantee visibility in low-light conditions. Additionally, verify that the base fabric is colorfast and resistant to UV degradation to prevent fading.