I've never heard of them either, but Wikipedia has (see examples at the end):

Nickel silver as used in cymbal making is an alloy of copper and nickel, and an alloy with about 12% nickel is used for some beginners' cymbals. A very few specialised high-quality cymbals are also made from nickel silver, as are some top-quality gongs tending to the more modern and exotic sounds.

Some maintain that the term nickel silver should only be used for alloys containing an appreciable content of zinc, and would call this cymbal alloy nickel bronze instead, but the use of the term nickel silver for all cymbal bronzes with nickel as the main alloying metal is well established.

Nickel silver is malleable and available as commercial sheet metal, and gives a bright tone but without the shimmer and sensitivity of tin bronzes. In the early to mid 20th century nickel alloy cymbals were far more widely produced and used, and so many older recordings were probably made using cymbals with a significant nickel content.

Examples of nickel silver cymbals include: Some Foremost, Meinl Streamer and Marathon N12, Paiste 402 and some Exotic Percussion, Sabian Signature Glennies Garbage, and some Zilco.

And if you go here: you will see that they were introduced in 1982.

Thanks for the info! They sound OK actually, better than a lot of the budget bronze today - the hat's are very responsive

They are from the 80's - I had a set when I was in my teens (in the 80s) that consisted of the following Meinl Streamers:

20" Ride

18" Crash

16" Crash

14" Medium Hats

10" Splash

I sold the hats, cracked the ride and the 18" and I still have the 16" and the splash.

I remember them as being pretty decent budget cymbals and they were inexpensive.