optocouplers

Hi all, my first post, so please bear with me. I have some older 4N25 optocouplers, stamped QTC 4N25 0130K [the 0130K part is to be taken with caution as the font is very small and hard to read]; the other brand, which was purchased recently is stamped T EL 4N25 224. Strangely to me [an amateur]...