As I remember the ones we used were plastic. They came in white and we spray painted them black. (It was a real thin plastic) we then used the pvc and base to stand them up, and brought them on the field inside the large backdrops.
At one point in my dot book...
16 counts...1-12 to side 1..count 13 hit light post... count 14-16 to set....
lol...