The Strad-O-Lin company of Chicago, active in the 1940s, farmed out some of its production to various small-shop luthiers, resulting in a wide variation in quality among its acoustic mandolins. Some are merely adequate, and some are quite nice. The company also produced a few electrics. The one on the left is definitely a Strad-O-Lin, but I'm not sure about the one on the right. (I have played one, and it wasn't that exciting.) As for the one below, it appears to be an oval-hole acoustic that someone tricked out with a pair of pickups.