looking for info on blades for Schick injector razors

[CDinVT]

I have been using yellow package Schick injector blades made in China aka "sChicks" in my vintage Schick injectors for a couple months I've been getting awesome shaves with them . I'm curious about the other brands. I know about Personna ,and supply .Is it true that supply plastic injector wont work with vintage Schick razors ? Is there any other manufacturers I'm missing out on . Thanks 

[Whiterook]

I haven't tried it, but the Black Label key looks way too thick for a vintage razor.  Load the blade into an empty Chick key, it's easy.  The only other blade I know of are the Schick Prolines.  No key on those, so see above.  I haven't tried those because I am happy with the other choices.

[Dave in KY]

I had 3 Supply Black Label blades sent to me to try and have been pleased with them. Also use the sChick blades with success.

[riverrun]

Chicks are the best choice, especially if you are in the US. Be content. Other blades are only marginally better.
Personna blades are OK, but I'm not too fond of their plastic magazines. In the worst-case transfer them to a Chick magazine.
You can't beat them for price and a lot of shavers like them.
Schick Prolines are really good, but not as easy to get hold of and not really cheap. You need to transfer them to a proper magazine as they come in key-less magazines.
Excellent blades though. Well worth getting.
There are Schick blades from Japan, both single and twin blades. Brilliant blades, but these days at eye-watering prices.
You need to order them from Japan.
I'd keep an eye out for vintage blades as well. Anything from 1965-ish onwards is a good bet. Avoid older blades as they were not stainless steel and are usually in really bad condition.
If you manage to get hold of the legendary Personna 74 blades... they are the best. Ever. Good luck getting them for less than $5 per blade. If they show up at all.
Vintage twin blades are great as well, but they are almost as rare as the Personna 74 blades and they usually come in magazines holding two blades only. Which makes them very expensive as well.

TL;DR: Stick with the Chicks.

[GAW9576]

Chicks are the best choice, especially if you are in the US. Be content. Other blades are only marginally better.
Personna blades are OK, but I'm not too fond of their plastic magazines. In the worst-case transfer them to a Chick magazine.
You can't beat them for price and a lot of shavers like them.
Schick Prolines are really good, but not as easy to get hold of and not really cheap. You need to transfer them to a proper magazine as they come in key-less magazines.
Excellent blades though. Well worth getting.
There are Schick blades from Japan, both single and twin blades. Brilliant blades, but these days at eye-watering prices.
You need to order them from Japan.
I'd keep an eye out for vintage blades as well. Anything from 1965-ish onwards is a good bet. Avoid older blades as they were not stainless steel and are usually in really bad condition.
If you manage to get hold of the legendary Personna 74 blades... they are the best. Ever. Good luck getting them for less than $5 per blade. If they show up at all.
Vintage twin blades are great as well, but they are almost as rare as the Personna 74 blades and they usually come in magazines holding two blades only. Which makes them very expensive as well.

TL;DR: Stick with the Chicks.

I was also under the impression that the twin blades only worked in the H and later razors. Is that correct? 
I have some Personna blades from https://connaughtshaving.com/injectorblades.html and greatly prefer them to the sChicks. I also have some 74s and although they are great blades was not personally blown away by them. I'm glad I actually got them for a considerably lower price than they usually go for.

[riverrun]

I was also under the impression that the twin blades only worked in the H and later razors. Is that correct? 

Correct.