which holley is this?

[292farmer]

i was in the second hand store down the road from my place when i spied this 4bbrl from across the room in the tool section i was amazed to see a holley 4 bbl plus a 1 in spacer looking in great shape, and the killer was it was 14bucks!!
i took it to the owner, (who i know and trust) asked if he knew the condition and he said his friend got it from a garage he works at that took it off a running customers car to replace it with a edelbrock needless to say for 14$ i snagged it, i found these numbers on it
1850-9 2015 8050b im curious which holley is this? 500, 650, 700cfm? or anything else about it, thanks