That appears to me to be a singer 99, it is considered a "compact" or 3/4 size machine. It uses the same bobbins as the larger 66 series machines. It is a drop in bobbin and will be a wonderful quiet durable straight stitch only machine. This machine has no reverse, never the less it will make beautiful raven stitches and the are thought very highly of by most who own them. I have 2 and like them very much. Yours appears to be in nice cosmetic shape. Read the sticky on how to clean and oil them and it should be ready to go in no time.Nice find and welcome to the world of vintage machines.