this seems to be mainly a wifi box. but it does have 4 ethernet ports.
Just like the cheapest MP3 players nowadays are smartphones, the cheapest “4 port switches” come with wifi (and probably with a 5th “WAN” port while at it).
Many of those cheap wifi routers with 4 ethernet ports have OpenWRT support, and while most of them include some blobs (there are currently no 100% Free wifi drivers for anything beyond 11n 
), the blobs are usually needed only for the wifi, so you should be able to deblob the OpenWRT image and still have a functioning (and 100% Free) ethernet switch.