It's a Singer 24x1 needle. Not sure what the equivalent is. Did you try Googling Singer Model 20 needles? Sometimes you can find a source that way.
I found this one:
http://www.suncatcher-tx.com/shop/To...s-sku-1206.htm
but others showed up, too.
Here's a list of machines & needles from the ISMACS site. It is useful for also finding manufacturers of machines.
http://www.ismacs.net/needle_and_sha...eedle-list.pdf