What year are these rotors?

[ericconn]

Hi, my dad used to run a shop that worked on a lot of imports and I came  across some Mazda rotors that are NOS still in their original  packaging. I can\'t find a part manual anywhere and searching online  hasn\'t turned up anything. I\'d like to eventually sell them to someone  who needs them and not just scrap them. Part number for one is:  2090-23-113B. Other one is probably the same part. Thanks a lot for any  help!
 

[TRIND-FD]

Says fc 13b on the box

[m1tch]

What are the weight letters? If they are a matched pair they could be useful to someone!

[Brett]

Do you have any pictures of the rotor faces, so i can see the pocket...?

[m1tch]

You thinking low compression series 4 rotors?

[HaywardRotary]

they are very early rotors and are either 12a or 10a due to the double side seals.
12a rotors are 70mm width,10a are 60mm width.
Regards
Carl

[ericconn]

They\'re at my mom\'s house, I\'ll get photos of them the next time I\'m up there.

[HaywardRotary]

On the early 12as and 10as you can see the apex seals were six wide. These rotors are clearly that way too.