Some kind of light? Reflector? Any ideas?

Metal looking inside triangle with round corners, red transparent same triangle with round corners shape outside like you would see on a bike, back has screws and a circle where something could fit inside for a battery or something?
https://imgur.com/TCLtSme
https://imgur.com/Unl4Ph0
https://imgur.com/qzRwkum
https://imgur.com/hzo9nO2