Abstract: The invention provides new reflective markers, reflectors, and delineators with a variety of mounting apparatuses for attaching the same onto standard guardrails in an efficient and effortless manner, without affecting the safety feature, display utility, and visibility of the marker/reflectors/delineators mounted thereon. The present invention also provides a new guardrail reflector/delineator that is particularly useful in situations, locations, and/or places with limited or no lighting, for example, cloudy days, foggy areas, dark places, streets with no lights at night, etc.