White reflectors in the Aero taillights?

[mpc]

What is the purpose of the white reflector that clips in to the top portion of the Willys Aero taillight housings?  Is it just to help spread the light from the bulb below?

Does anyone have a source for these to purchase?  They look fairly generic.  I found a NOS set online for $30, but I'm thinking I could find a cheaper alternative.

Thank you.

[mpc]

Well I guess these are easy enough to find as a  standard 1.25" mini reflector:
https://www.lowes.com/pd/Hillman-9-in-Mini-Reflectors/3058189

Everything I've found so far has a peel off sticky back, but I can take that off and clean it. 
I still find these to be a curious component in the housing and I'm interested to see what effect these have on the overall brightness.

[RT]

My understanding of the reflector is, the rear of cars must have red reflectors to identify the rear of the car if the lights are not on or if the car is parked with the lights off so approaching drivers can identify the rear of another car.
The white reflectors are there because the Willys taillight red lens does not have a reflector built-in.  The clear reflector is behind the red plastic and will reflect the light back through the red lens to appear red behind the car.

RT

[mpc]

That makes sense! Thank you for that information.