Unknown memory expansion for Amiga 500

[psxphill]

Dear All,
I have looked all over the Amiga Hardware Database but I have not found the picture of a memory card I have found in a "new" Amiga 500!
I am almost sure it is there (since I have always found everything) but I haven't found it.
The Italian sentence only mean "exact side for connection".
There is also a 3 way switch.
Can somebody help?
Thank you

There are 4 256k x 4bit memory chips on it, so it's a 1 mb memory card with a single pole, double throw (on/off) switch.

It's for the a500+, to give you 2mb of chip ram. There were lots of clone cards, you won't find them all documented.

[psxphill]

Thank you for the help.
I do not have an A500+ to test. Could it be that the switch is used to select 512kb or 1Mb?
mmm...  4 x 256kbit x 4bit is 512 kbyte, right?

oops yeah, my mental arithmetic is not what it was.